Combination vaccine

Abstract

The present disclosure relates to compositions comprising multiple antigens of interest for use in vaccine formulations. The compositions comprise (a) a polynucleotide (such as an RNA) comprising a nucleotide sequence encoding an antigen and (b) an antigen polypeptide. The compositions can be used in inducing an immune response in a subject and / or in the treatment or prevention of a disease, such as a respiratory viral infection.

Description

[0001]COMBINATION VACCINE RELATED APPLICATION DATA The present application claims priority from United States Patent Application No. 63 / 501,222 filed 10 May 2023 entitled “Combination vaccine”, the entire contents of which is hereby incorporated by reference. SEQUENCE LISTING The present application is filed together with a Sequence Listing in electronic form. The entire contents of the Sequence Listing are hereby incorporated by reference. FIELD The present disclosure relates to compositions comprising multiple antigens of interest for use in vaccine formulations. BACKGROUND Respiratory viral infections are a significant threat to human health. Infections, such as those caused by the influenza virus and severe acute respiratory syndrome coronavirus (SARS-CoV) have been known to cause global pandemics, killing millions of people worldwide. Recently, SAR-CoV-2 has been responsible for causing the on- going worldwide pandemic of the severely infectious coronavirus disease 2019 (COVID- 19). Moreover, respiratory syncytial virus (RSV) is the single most common cause of respiratory hospitalization in infants, and reinfection remains common in later life. Whilst some vaccines are available for viral infections such as influenza, SARS-CoV-2 and RSV, such as mRNA vaccines developed to treat or prevent a SARS-CoV-2 infection, further improvements can be made to increase their efficacy and / or improve treatment strategies. Currently, egg-based manufacturing processes are the most common way that vaccines are produced. This process requires a significant amount of time to optimize virus growth in the eggs, as well as resources (i.e., eggs) to produce sufficient amounts of vaccine, particularly during a pandemic. Furthermore, given the long development time required, vaccine strain selection is conducted before the vaccine is made available, making it difficult to respond to changes in the virus. Vaccines have also been produced using cell-based manufacturing processes involving cultured mammalian cells (e.g. Madin-Darby Canine Kidney, or MDCK cells) in place of eggs, and viral-based platforms involving recombinant virus (e.g. baculovirus encoding an antigen of influenza) have also been utilised. There remains a need for the development of specific and efficient viral vaccines that can be produced more rapidly and with broader utility than current egg-based techniques, for the treatment or prevention of respiratory viral infections, such as influenza, RSV and SARS-CoV-2. Nucleic acid-based vaccines offer distinct advantages over the current egg-based manufacturing platform, although some challenges remain. For example, the inherently labile nature of mRNA results in most RNA-based vaccines having limited ability to provide antigen at a dose and duration required to produce a strong, durable immune response. Therefore, it will be apparent to the skilled person that there is a need in the art for compositions with broader utility and / or improved efficacy that are suitable for use as vaccines. SUMMARY The present disclosure is based on the inventors’ findings that combining an RNA-based antigen with a protein-based antigen in an immunogenic composition, such as a vaccine, can enhance a subject’s immune response to the immunogenic composition. The inventors additionally found that administering a coformulated RNA vaccine, e.g., a self amplifying mRNA (sa-mRNA) vaccine and an adjuvanted protein-based vaccine results in enhanced neutralization titers against the antigens of both vaccines and influence the the subclasses of antigen-specific IgG induced by recombinant protein vaccines. For example, the inventors found the ratio of antigen-specific IgG1:IgG2a induced by adjuvanted protein vaccine was significantly shifted towards a balanced IgG1:IgG2a response when coformulated with a RNA vaccine, e.g., a self amplifying mRNA (sa-mRNA) vaccine. These improvements were found compared to, e.g., RNA vaccines and protein vaccines that are co administered at distal sites from one another The inventors additionally found that a RNA vaccine and a protein vaccine locally coadministered provided similar benefits to a co-formulated RNA vaccine and protein vaccine compared to RNA vaccines and protein vaccines that are co administered at distal sites from one another. The findings by the inventors therefore provide basis for immunogenic compositions comprising (i) a RNA comprising a nucleotide sequence encoding one or more antigens of interest selected from the group consisting of a respiratory syncytial virus (RSV), an influenza virus and / or a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (ii) a polypeptide antigen selected from the group consisting of a RSV, an influenza virus and / or a SARS-CoV-2. Furthermore, the findings by the inventors provide basis for methods of treating or preventing or delaying progression of a disease or disorder (e.g., a RSV, influenza, a SARS-COV-2 infection, COVID-19 or ARDS) in a subject by administering the immunogenic compositions of the disclosure. Accordingly, the present disclosure provides an immunogenic composition comprising: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen selected from the group consisting of a respiratory syncytial virus (RSV), influenza and a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (ii) an antigen polypeptide selected from the group consisting of a RSV, influenza and a SARS-CoV-2. When discussing an antigen selected from the group consisting of a respiratory syncytial virus (RSV), influenza and a severe acute respiratory syndrome coronavirus (SARS-CoV-2) the skilled artisan will recognize that the antigen is from the recited virus. In an example, the immunogenic composition comprises: a) a polynucleotide comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: a) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: a) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: a) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: a) a polynucleotide comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a polynucleotide comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: a) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2. In an example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen selected from the group consisting of a respiratory syncytial virus (RSV), an influenza virus and / or a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (ii) an antigen polypeptide selected from the group consisting of a RSV, an influenza virus and / or a SARS-CoV-2. In an example, the immunogenic composition comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2. In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen selected from the group consisting of a respiratory syncytial virus (RSV), an influenza virus and / or a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (ii) an antigen polypeptide selected from the group consisting of a RSV, an influenza virus and / or a SARS-CoV-2. In an example, the immunogenic composition comprises: a) a cRNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: a) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: a) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: a) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: a) a cRNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a cRNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a RSV. In another example, the immunogenic composition comprises: a) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2. In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen selected from the group consisting of a respiratory syncytial virus (RSV), an influenza virus and / or a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (ii) an antigen polypeptide selected from the group consisting of a RSV, an influenza virus and / or a SARS-CoV-2. In an example, the immunogenic composition comprises: a) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: a) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: a) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: a) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: a) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a RSV. In another example, the immunogenic composition comprises: a) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: a) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2. In one example, an immunogenic composition of the disclosure comprises multiple polynucleotides, wherein each polynucleotide encodes different polypeptide sequences. In another example, an immunogenic composition of the disclosure comprises multiple RNAs, wherein each RNA encodes different polypeptide sequences. In a further example, an immunogenic composition of the disclosure comprises multiple cRNAs, wherein each cRNA encodes different polypeptide sequences. In a further example, an immunogenic composition of the disclosure comprises multiple self- replicating RNAs, wherein each self-replicating RNA encodes different polypeptide sequences. Thus, in an example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV); (ii) the polynucleotide comprising a nucleotide sequence encoding an antigen from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, and (ii) the polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); (ii) the polynucleotide comprising a nucleotide sequence encoding an antigen from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the polynucleotide comprising a nucleotide sequence encoding an antigen from influenza; and (ii) the polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); (ii) the polynucleotide comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the polynucleotide comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and (ii) the polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV); (ii) the RNA comprising a nucleotide sequence encoding an antigen from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from influenza, and (ii) the RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); (ii) the RNA comprising a nucleotide sequence encoding an antigen from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from influenza; and (ii) the RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); (ii) the RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and (ii) the RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the cRNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV); (ii) the cRNA comprising a nucleotide sequence encoding an antigen from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the cRNA comprising a nucleotide sequence encoding an antigen from influenza, and (ii) the cRNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); (ii) the cRNA comprising a nucleotide sequence encoding an antigen from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the cRNA comprising a nucleotide sequence encoding an antigen from influenza; and (ii) the cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); (ii) the cRNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the cRNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and (ii) the cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV); (ii) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, and (ii) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); (ii) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza; and (ii) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); (ii) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises, in order from 5’ to 3’: (i) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and (ii) the self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In one example, an immunogenic composition comprises multiple multicistronic self-replicating RNAs, wherein each multicistronic self-replicating RNA encodes a polypeptide of an antigen of interest. In another example, an immunogenic composition of the disclosure comprises a plurality of self-replicating monocistronic RNAs, wherein each self-replicating RNA encodes different polypeptide sequences. For example, one self-replicating RNA encodes a polypeptide of an antigen of interest and a different self- replicating RNA encodes a different polypeptide of an antigen of interest. In one example of the present disclosure, the immunogenic composition comprises multiple polypeptide antigens, wherein each polypeptide is a different antigen of interest. In another embodiment, the different polypeptide of an antigen of interest may be from the same virus. For example, different polypeptides may be from a respiratory syncytial virus (RSV), a severe acute respiratory syndrome coronavirus (SARS-CoV-2) or influenza. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a respiratory syncytial virus (RSV); and (iii) a further polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) a further antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) a further antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In an example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a respiratory syncytial virus (RSV); and (iii) a further polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) a further antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) a further antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In an example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a respiratory syncytial virus (RSV); and (iii) a further polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) a further antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a cRNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) a further antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) an antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a respiratory syncytial virus (RSV); and (iii) a further polypeptide from a respiratory syncytial virus (RSV). In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) a further antigen polypeptide from influenza. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising a nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and (iii) a further antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In an example, the compositions described herein further comprise an adjuvant. In an example of the disclosure a protein antigen is formulated with an adjuvant. In one example, the adjuvant is selected from the group consisting of Freund's adjuvant, incomplete Freund's adjuvants, aluminum phosphate, aluminum hydroxide, GMCSP, BCG, MDP compounds, such as thur-MDP and nor-MDP, CGP (MTP-PE), lipid A, monophosphoryl lipid A (MPL), RIBI, MPL, trehalose dimycolate (TDM), Novasomes®, QS21, Quil A (and derivatives and components thereof), calcium phosphate, calcium hydroxide, zinc hydroxide, MHC antigens, PolyI:C, MF59, glycolipid analogs, octodecyl esters of an amino acid, muramyl dipeptides, polyphosphazene, lipoproteins, ISCOM matrix, DC-Chol, ODA, cytokines, and other adjuvants and derivatives thereof. In another example, the adjuvant is MF59. In an example, the effect of an immunogenic composition described herein, on treating, preventing or delaying progression of a disease or disorder is enhanced in the presence of an adjuvant such as MF59, when compared to the effect of an immunogenic composition described herein without an adjuvant. In an example, the effect of an immunogenic composition described herein, on treating, preventing or delaying progression of a SARS-CoV-2 infection, COVID-19, influenza and / or respiratory syncytial virus (RSV) is enhanced in the presence of an adjuvant such as MF59, when compared to the effect of an immunogenic composition described herein without an adjuvant. In an example, the effect of an immunogenic composition described herein, on treating, preventing or delaying progression of pneumonia, sepsis or acute respiratory distress syndrome in a subject having COVID-19 is enhanced in the presence of an adjuvant such as MF59, when compared to the effect of an immunogenic composition described herein without an adjuvant. In an example, the effect of an immunogenic composition described herein, on treating, preventing or delaying progression of an influenza infection is enhanced in the presence of an adjuvant such as MF59, when compared to the effect of an immunogenic composition described herein without an adjuvant. In an example, the effect of an immunogenic composition described herein, on treating, preventing or delaying progression of a RSV infection is enhanced in the presence of an adjuvant such as MF59, when compared to the effect of an immunogenic composition described herein without an adjuvant. In an example, the effect of an immunogenic composition described herein, on inducing an immune response in a subject is enhanced in the presence of an adjuvant such as MF59, when compared to the effect of an immunogenic composition described herein without an adjuvant. In an example, the presence of an adjuvant such as MF59 in an immunogenic composition described herein enhances the induction of the immune response of the composition by at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55% at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 100%, at least about 200%, at least about 300%, at least about 400%, at least about 500% or more when compared to the effect of an immunogenic composition described herein without an adjuvant such as MF59. In an example, the adjuvant is administered at the same time as an immunogenic composition of the disclosure. In another example, the adjuvant is administered sequentially to, preceding, or proceeding the administration of an immunogenic composition of the disclosure. In one example, a composition described herein further comprises an additional polypeptide selected from the group consisting of: (i) one or more antigens; (ii) one or more immunopotentiating agents; (iii) one or more chemoattractants; and / or (iv) one or more targeting molecules. In an example, the nucleotide sequence is operably linked to a regulatory element selected from the group consisting of a promoter, optionally a subgenomic (SG) promoter, an internal ribosome entry site (IRES) and a Kozak consensus sequence or a combination thereof. In an example, the regulatory element is a SG promoter. For example, the polynucleotide of the immunogenic composition comprises a nucleotide sequence encoding an antigen operably linked to a regulatory element selected from a SG promoter, and IRES and / or a Kozak consensus sequence. In another example, the RNA of the immunogenic composition comprises a nucleotide sequence encoding an antigen operably linked to a regulatory element selected from a SG promoter, and IRES and / or a Kozak consensus sequence. In another example, the cRNA of the immunogenic composition comprises a nucleotide sequence encoding an antigen operably linked to a regulatory element selected from a SG promoter, and IRES and / or a Kozak consensus sequence. In another example, the self-replicating RNA of the immunogenic composition comprises a nucleotide sequence encoding an antigen operably linked to a regulatory element selected from a SG promoter, and IRES and / or a Kozak consensus sequence. Accordingly, the present disclosure provides an immunogenic composition comprising: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from influenza. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. Accordingly, the present disclosure also provides an immunogenic composition comprising: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV- 2), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from influenza. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. Accordingly, the present disclosure also provides an immunogenic composition comprising: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV- 2), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from influenza. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. Accordingly, the present disclosure also provides an immunogenic composition comprising: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from influenza. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2); and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV); and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. The present disclosure further provides an immunogenic composition comprising (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from SARS-CoV-2 operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV- 2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from influenza. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. The present disclosure also provides an immunogenic composition comprising (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a SARS-CoV-2. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from influenza. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. The present disclosure also provides an immunogenic composition comprising (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a SARS-CoV-2. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from influenza. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. The present disclosure also provides an immunogenic composition comprising (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES; and (ii) an antigen polypeptide from influenza. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a Kozak consensus sequence, an IRES, a SG promoter and combinations thereof; and b) a second nucleotide sequence encoding a first antigen antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. The present disclosure provides an immunogenic composition comprising: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV- 2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV- 2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. The present disclosure provides an immunogenic composition comprising: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV- 2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from SARS-CoV-2 operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from SARS-CoV-2 operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV- 2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. The present disclosure provides an immunogenic composition comprising: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a SARS-CoV-2 operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV- 2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV- 2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a Kozak consensus sequence and a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a Kozak consensus sequence and an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. The present disclosure provides an immunogenic composition comprising: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from SARS-CoV-2 operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a SG promoter; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. The present disclosure provides an immunogenic composition comprising: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a polynucleotide comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the polynucleotide comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a cRNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the cRNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In another example, the present disclosure provides an immunogenic composition comprising: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a severe acute respiratory syndrome coronavirus (SARS-CoV-2). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from respiratory syncytial virus (RSV) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from influenza, operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In an example, the immunogenic composition comprises: (i) a self-replicating RNA comprising: a) a first nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES, and (ii) an antigen polypeptide from influenza. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the self-replicating RNA comprises, in order from 5’ to 3’: a) a first nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), operably linked to an IRES; and b) a second nucleotide sequence encoding an antigen from a severe acute respiratory syndrome coronavirus (SARS-CoV-2) operably linked to a regulatory element selected from the group consisting of a SG promoter and an IRES. In one example, the disclosure additionally provides an immunogenic composition comprising: (i) a F protein from RSV; and (ii) a sa-mRNA encoding a HA from influenza. In one example, the disclosure additionally provides an immunogenic composition comprising: (i) a F protein from RSV; and (ii) a sa-mRNA encoding a HA and a NA from influenza. In one example, the disclosure additionally provides an immunogenic composition comprising: (i) a F protein from RSV; and (ii) a plurality of sa-mRNAs each sa-mRNA encoding a HA from influenza. In one example, the disclosure additionally provides an immunogenic composition comprising: (i) a F protein from RSV; and (ii) a plurality of sa-mRNAs each sa-mRNA encoding a HA and a NA from influenza. In one example, the disclosure additionally provides an immunogenic composition comprising: (i) a F protein from RSV; and (ii) three or more sa-mRNAs each sa-mRNA encoding a HA from influenza. In one example, the disclosure additionally provides an immunogenic composition comprising: (i) a F protein from RSV; and (ii) three or more sa-mRNAs each sa-mRNA encoding a HA and a NA from influenza. (i) a F protein from RSV; and (ii) four or more sa-mRNAs each sa-mRNA encoding a HA from influenza. In one example, the disclosure additionally provides an immunogenic composition comprising: (i) a F protein from RSV; and (ii) four or more sa-mRNAs each sa-mRNA encoding a HA and a NA from influenza. In some examples, e.g., where multipe sequence encoding antigens are included in a single sa-mRNA, the first nucleotide sequence is operably linked to a SG promoter and the second nucleotide sequence is operably linked to a SG promoter. In one example, the SG promoter is a native SG promoter. For example, a native SG promoter is a promoter that is native to the RNA virus from which it is derived and / or based on (e.g., an alphavirus). In one example, the native SG promoter is a native alphavirus SG promoter. In some examples, the SG promoter is encoded by a sequence comprising or consisting of SEQ ID NO: 32. In one example, the SG promoter is a minimal SG promoter or an extended SG promoter. In one example, the SG promoter is a minimal SG promoter. In one example, the native SG promoter is a minimal SG promoter. For example, the minimal SG promoter is the minimal sequence required for initiation of transcription. In one example, the minimal native SG promoter is 49 nucleotides in length. In one example, the minimal SG promoter is 49 nucleotides in length. In one example, the minimal native SG promoter is encoded by a sequence comprising or consisting of a sequence set forth in SEQ ID NO: 13. In one example, the minimal SG promoter is encoded by a sequence comprising or consisting of a sequence set forth in SEQ ID NO: 13. In one example, the SG promoter is an extended SG promoter. In one example, the native SG promoter is an extended SG promoter. For example, the extended SG promoter is extended at the 5’ end with nucleotides occurring in a sequence encoding a non-structural protein (e.g., NSP4) of the RNA virus (e.g., an alphavirus). In one example, the extended SG promoter is extended at the 5’ end with nucleotides occurring in a sequence encoding an alphavirus NSP4. The addition of nucleotides to the 5’ end of the SG promoter sequence did not interfere with expression of the non-structural protein and viral replicase, e.g., alphavirus NSP4. In one example, the SG promoter is extended at the 5’ end by 51 or fewer nucleotides occurring in a sequence encoding a non-structural protein (e.g., an alphavirus NSP4). In one example, the extended SG promoter is a minimal SG promoter extended at the 5’ end by no more than 51 nucleotides occurring in a sequence encoding a non- structural protein (e.g., an alphavirus NSP4). In one example, the extended SG promoter is encoded by a sequence comprising or consisting of a sequence set forth in SEQ ID NO: 13 extended at the 5’ end by no more than 51 nucleotides occurring in a sequence encoding a non-structural protein (e.g., an alphavirus NSP4). For example, the extended SG promoter is no more than 100 nucleotides in length. In one example, the extended SG promoter is encoded by a sequence comprising or consisting of nucleotides 2 to 101 of SEQ ID NO: 17. In one example, the SG promoter is extended at the 5’ end by about 5 nucleotides to about 20 nucleotides, for example by about 5 nucleotides, or about 10 nucleotides, or about 12, or about 15 nucleotides, or about 20 nucleotides, occurring in a sequence encoding a non-structural protein (e.g., an alphavirus NSP4). In another example, the SG promoter is extended at the 5’ end by about 20 to about 35 nucleotides, for example, by about 25 nucleotides or about 27 nucleotides, or about 30 nucleotides, or about 35 nucleotides, occurring in a sequence encoding a non-structural protein (e.g., an alphavirus NSP4). In one example, the SG promoter is extended at the 5’ end by about 12 nucleotides occurring in a sequence encoding a non-structural protein (e.g., an alphavirus NSP4). In one example, the extended SG promoter is encoded by a sequence set forth in SEQ ID NO: 13 extended at the 5’ end by 12 nucleotides occurring in a sequence encoding a non- structural protein (e.g., an alphavirus NSP4). For example, the extended SG promoter is no more than 61 nucleotides in length. In one example, the extended SG promoter is encoded by a sequence comprising or consisting of nucleotides 41 to 101 of SEQ ID NO: 17. In another example, the extended SG promoter is encoded by a sequence comprising or consisting of a sequence set forth in SEQ ID NO: 14. In one example, the SG promoter is extended at the 5’ end by about 31 nucleotides occurring in a sequence encoding a non-structural protein (e.g., an alphavirus NSP4). In one example, the extended SG promoter is encoded by a sequence set forth in SEQ ID NO: 13 extended at the 5’ end by 31 nucleotides occurring in a sequence encoding a non- structural protein (e.g., an alphavirus NSP4). For example, the extended SG promoter is no more than 80 nucleotides in length. In one example, the extended SG promoter is encoded by a sequence comprising or consisting of nucleotides 22 to 101 of SEQ ID NO: 17. In another example, the extended SG promoter is encoded by a sequence comprising or consisting of a sequence set forth in SEQ ID NO: 15. In one example, the extended SG promoter comprises a repeat sequence corresponding to nucleotides 66 to 75 of SEQ ID NO: 17. For example, the extended SG promoter is encoded by a sequence comprising nucleotides 50 to 75 of SEQ ID NO: 17 and nucleotides 66 to 101 of SEQ ID NO: 17. For example, the extended SG promoter is encoded by a sequence set forth in SEQ ID NO: 27. In one example, the IRES is an IRES from encephalomyocarditis virus (EMCV), poliovirus (PV), human enterovirus, foot-and-mouth disease virus (FMDV), hepatitis C virus (HCV), classical swine fever virus (CSFV), murine leukemia virus (MLV), simian immunodeficiency virus (SIV), Eukaryotic translation initiation factor 4G (elF4G), Death-associated protein 5 (DAP5), cellular Myc (c-Myc), NF-κB-repressing factor (NRF), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF-2), platelet-derived growth factor B (PDGF B), Antennapedia, X-linked inhibitor of apoptosis (XIAP or Apaf-1), immunoglobulin heavy-chain binding protein BiP, or fibroblast growth factor 1a (FGF1A), GTX, or a combination thereof. In one example, the IRES is a wild-type IRES derived from encephalomyocarditis virus (EMCV). For example, the wild-type EMCV IRES comprises a sequence set forth in SEQ ID NO: 16. In one example, the nucleotide sequence is codon optimized. In one example, the G / C content of the nucleotide sequence is modified. In one example, the G / C content of the nucleotide sequence is increased by at least 5% compared to the G / C content of the unmodified sequence. For example, the G / C content of the first and / or second nucleotide sequence and / or the one or more additional nucleotide sequences is increased by at least 10%, or 15%, or 20%, or 25%, or 30%, or 35%, or 40% compared to the G / C content of the unmodified sequence. In one example, the polynucleotide comprises at least one chemically modified nucleotide. In one example, the chemically modified nucleotide is selected from the group consisting of N6,2’-O-dimethyl-adenosine (m6Am), 5-methyluridine (m5U), N4- acetylcytidine (ac4C), 2-thiocytidine (s2C), 2-thiouridine (s2U), 5-methylcytidine (m5C), N6-methyladenosine (m6a), pseudouridine (ψ), 1-methylpseudouridine (m1ψ), and combinations thereof. For example, the chemically modified nucleotide is N6,2’-O- dimethyl-adenosine (m6Am). For example, the chemically modified nucleotide is 5- methyluridine (m5U). For example, the chemically modified nucleotide is N4- acetylcytidine (ac4C). For example, the chemically modified nucleotide is 2-thiocytidine (s2C). For example, the chemically modified nucleotide is 2-thiouridine (s2U). For example, the chemically modified nucleotide is 5-methylcytidine (m5C). For example, the chemically modified nucleotide is N6-methyladenosine (m6a). For example, the chemically modified nucleotide is pseudouridine (ψ). For example, the chemically modified nucleotide is 1-methylpseudouridine (m1ψ). In one example, the nucleotide sequence comprises the 5’-UTR of haptoglobin (HP), fibrinogen beta chain (FGB), haptoglobin-related protein (HPR), albumin (ALB), complement component 3 (C3), fibrinogen alpha chain (FGA), alpha 6 collagen (Col6A), alpha-1-antitrypsin (SERPINA1), alpha-1-antichymotrypsin (SERPINA3) a fragment and / or a variant thereof. In one example, the 5’UTR is a 5’UTR of a Venezuelan equine encephalitis virus (VEEV) or modified forms thereof. For example, the 5’UTR comprises a sequence set forth in SEQ ID NO: 25. In one example, the 5’-UTR, the fragment and / or the variant thereof is between 40 and 2000 nucleotides in length. For example, the 5’-UTR, the fragment and / or the variant thereof is between 40 and 100 nucleotides in length. For example, the 5’-UTR, the fragment and / or the variant thereof is between 100 and 250 nucleotides in length. For example, the 5’-UTR, the fragment and / or the variant thereof is between 250 and 500 nucleotides in length. For example, the 5’-UTR, the fragment and / or the variant thereof is between 500 and 750 nucleotides in length. For example, the 5’-UTR, the fragment and / or the variant thereof is between 750 and 1000 nucleotides in length. For example, the 5’-UTR, the fragment and / or the variant thereof is between 1000 and 1250 nucleotides in length. For example, the 5’-UTR, the fragment and / or the variant thereof is between 1250 and 1500 nucleotides in length. For example, the 5’-UTR, the fragment and / or the variant thereof is between 1500 and 1750 nucleotides in length. For example, the 5’-UTR, the fragment and / or the variant thereof is between 1750 and 2000 nucleotides in length. In one example, the 5’-UTR, the fragment and / or the variant thereof comprises a nucleotide sequence at least 90% identical to a nucleotide sequence set forth in any one of SEQ ID NO: 21 to 26. For example, the 5’-UTR, the fragment and / or the variant thereof comprises a nucleotide sequence 90%, or 91%, or 92%, or 93%, or 94%, or 95%, or 96%, or 97%, or 98%, or 99% identical to a nucleotide sequence set forth in any one of SEQ ID NO: 21 to 26. In one example, the polynucleotide comprises a combination of two or more 5’- UTRs, fragments and / or variants thereof. In one example, the two or more 5’-UTRs are the same. In one example, the two or more 5’-UTRs are different. In one example, the nucleotide sequence comprising the 5’UTR comprises at least one microRNA binding site, an AU rich element (ARE), a GC-rich element, a stem loop, and combinations thereof. In one example, the nucleotide sequence comprises a microRNA binding site. In one example, the nucleotide sequence comprises an AU rich element (ARE). In one example, the nucleotide comprises a GC-rich element. In one example, the nucleotide sequence comprises a stem loop. For example, the stem loop is a histone stem loop. In one example, the polynucleotide further comprises a nucleotide sequence comprising a 3’UTR. In one example, the nucleotide sequence comprising the 3’UTR is located 3’ of the second or the one or more additional nucleotide sequences. For example, the nucleotide sequence comprising the 3’UTR is located 3’ of the second nucleotide sequence. In one example, the 3’UTR comprises a 3’-UTR of arachidonate 5- lipoxygenase (ALOX5), alpha I collagen (COL1A1), tyrosine hydroxylase (TH) gene, amino-terminal enhancer of split (AES), human mitochondrial 12S rRNA (mtRNR1), a fragment and / or a variant thereof. In one example, the 3’UTR is a 3’UTR of a Sindbis virus (SINV) or modified forms thereof. For example, the 3’UTR comprises a sequence set forth in SEQ ID NO: 26. In one example, the 3’UTR, the fragment and / or the variant thereof is between 40 and 400 nucleotides in length. For example, the 3’-UTR is between 40 and 50, or 50 and 60, or 60 and 70, or 70 and 80, or 80 and 90, or 90 and 100, or 100 and 125, or 125 and 150, or 150 and 175, or 175 and 200, or 200 and 225, or 225 and 250, or 250 and 275, or 275 and 300, or 300 and 325, or 325 and 350, or 350 and 375, or 375 and 400 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 40 and 50 nculeotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 50 and 60 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 60 and 70 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 70 and 80 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 80 and 90 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 90 and 100 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 100 and 125 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 125 and 150 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 150 and 175 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 175 and 200 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 200 and 225 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 225 and 250 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 250 and 275 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 275 and 300 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 300 and 325 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 325 and 350 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 350 and 375 nucleotides in length. For example, the 3’-UTR, the fragment and / or the variant thereof is between 375 and 400 nucleotides in length. In one example, the polynucleotide comprises a combination of two or more 3’- UTRs, fragments and / or variants thereof. In one example, the two or more 3’-UTRs are the same. In one example, the two or more 3’-UTRs are different. In one example, the nucleotide sequence comprising the 3’UTR, the fragment and / or variant thereof comprises at least one microRNA binding site, an AU rich element (ARE), a GC-rich element, a triple helix, a stem loop, one or more stop codons and combinations thereof. In one example, the nucleotide sequence comprises a microRNA binding site. In one example, the nucleotide sequence comprises an AU rich element (ARE). In one example, the nucleotide sequence comprises a GC-rich element. In one example, the nucleotide sequence comprises a triple helix. In one example, the nucleotide sequence comprises a stem loop. For example, the stem loop is a histone stem loop. In one example, the nucleotide sequence comprises one or more stop codons. For example, the one or more stop codons are located at the 5’end of the 3’-UTR. In one example, the polynucleotide comprises a nucleotide sequence comprising one or more 3’ tailing sequences located at the 3’end of the nucleotide sequence comprising the 3’UTR. In one example, the one or more 3’ tailing sequences are selected from the group consisting of a poly-A sequence, polyadenylation signal, a G-quadruplex, a poly-C sequence, a stem loop and combinations thereof. For example, the 3’ tailing sequence comprises a poly-A sequence. In one example, the 3’ tailing sequence comprises a polyadenylation signal. In one example, the 3’ tailing sequence comprises a G-quadruplex. In one example, the 3’ tailing sequence comprises a poly-C sequence. In one example, the 3’ tailing sequence comprises a stem loop. For example, the stem loop is a histone stem loop. In one example, the 3’ tailing sequence comprises a poly-A sequence and a G-quadruplex. In one example, the 3’ tailing sequence comprises a stem loop (e.g., a histone stem loop) and a poly-A sequence. In one example, the one or more 3’ tailing sequences comprises one or more poly- A sequences each comprising between 10 and 300 consecutive adenosine nucleotides. For example, the poly-A sequences each comprises between 10 and 20, or 20 and 30, or 30 and 40, or 40 and 50, or 50 and 60, or 60 and 70, or 70 and 80, or 80 and 90, or 90 and 100, or 100 and 125, or 125 and 150, or 150 and 175, or 175 and 200, or 200 and 225, or 225 and 250, or 250 and 275, or 275 and 300 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 10 and 20 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 20 and 30 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 30 and 40 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprise 36 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 40 and 50 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 50 and 60 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 60 and 70 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 70 and 80 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 80 and 90 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 90 and 100 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 100 and 125 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 125 and 150 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 150 and 175 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 175 and 200 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 200 and 225 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 225 and 250 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 250 and 275 consecutive adenosine nucleotides. For example, the one or more poly-A sequences each comprises between 275 and 300 consecutive adenosine nucleotides. In one example, the one or more poly-A sequence each comprises 10, or 20, or 30, or 40, or 50, or 60, or 70, or 80, or 90, or 100, or 125, or 150, or 175, or 200, or 225, or 250, or 275, or 300 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 10 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 20 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 30 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 40 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 50 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 60 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 70 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 80 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 90 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 100 consecutive adenosine nucleotides. For example, the one or more poly- A sequence each comprises 125 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 150 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 175 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 200 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 225 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 250 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 275 consecutive adenosine nucleotides. For example, the one or more poly-A sequence each comprises 300 consecutive adenosine nucleotides. In one example, the poly-A sequence comprises 36 consecutive adenosine nucleotides. For example, the poly-A sequence comprises a sequence set forth in SEQ ID NO: 28. In one example, the one or more poly-A sequences is separated by an interrupting linker. For example, the 3’tailing sequence comprises, in order of 5’ to 3’: a poly-A sequence comprising consecutive adenosine nucleotides, an interrupting linker, and a further poly-A sequence comprising consecutive adenosine nucleotides. In one example, the interrupting linker is from 10 to 50, or 50 to 100, or 100 to 150 nucleotides in length. For example, the interrupting linker is from 10 to 50 nucleotides in length. For example, the interrupting linker is from 50 to 100 nucleotides in length. For example, the interrupting linker is from 100 to 150 nucleotides in length. In one example, the interrupting linker is 1, or 2, or 3, or 4, or 5, or 6, or 7, or 8, or 9, or 10, or 11, or 12, or 13, or 14, or 15, or 16, or 17, or 18, or 19, or 20, or 25, or 30, or 35, or 40, or 45, or 50, or 55, or 60, or 65, or 70, or 75, or 80, or 85, or 90, or 95, or 100, or 110, or 120, or 130, or 140, or 150 nucleotides in length. For example, the interrupting linker is 1 nucleotide in length. For example, the interrupting linker is 2 nucleotides in length. For example, the interrupting linker is 3 nucleotides in length. For example, the interrupting linker is 4 nucleotides in length. For example, the interrupting linker is 5 nucleotides in length. For example, the interrupting linker is 6 nucleotides in length. For example, the interrupting linker is 7 nucleotides in length. For example, the interrupting linker is 8 nucleotides in length. For example, the interrupting linker is 9 nucleotides in length. For example, the interrupting linker is 10 nucleotides in length. For example, the interrupting linker is 11 nucleotides in length. For example, the interrupting linker is 12 nucleotides in length. For example, the interrupting linker is 13 nucleotides in length. For example, the interrupting linker is 14 nucleotides in length. For example, the interrupting linker is 15 nucleotides in length. For example, the interrupting linker is 16 nucleotides in length. For example, the interrupting linker is 17 nucleotides in length. For example, the interrupting linker is 18 nucleotides in length. For example, the interrupting linker is 19 nucleotides in length. For example, the interrupting linker is 20 nucleotides in length. For example, the interrupting linker is 25 nucleotides in length. For example, the interrupting linker is 30 nucleotides in length. For example, the interrupting linker is 35 nucleotides in length. For example, the interrupting linker is 40 nucleotides in length. For example, the interrupting linker is 45 nucleotides in length. For example, the interrupting linker is 50 nucleotides in length. For example, the interrupting linker is 55 nucleotides in length. For example, the interrupting linker is 60 nucleotides in length. For example, the interrupting linker is 65 nucleotides in length. For example, the interrupting linker is 70 nucleotides in length. For example, the interrupting linker is 75 nucleotides in length. For example, the interrupting linker is 80 nucleotides in length. For example, the interrupting linker is 85 nucleotides in length. For example, the interrupting linker is 90 nucleotides in length. For example, the interrupting linker is 95 nucleotides in length. For example, the interrupting linker is 100 nucleotides in length. For example, the interrupting linker is 110 nucleotides in length. For example, the interrupting linker is 120 nucleotides in length. For example, the interrupting linker is 130 nucleotides in length. For example, the interrupting linker is 140 nucleotides in length. For example, the interrupting linker is 150 nucleotides in length. In one example, the interrupting linker is 10 nucleotides in length. In one example, the interrupting linker comprises or consists of the nucleotide sequence set forth in SEQ ID NO: 20. For example, the interrupting linker comprises or consists of a nucleotide sequence GCAUAUGACU. In one example, the 3’ tailing sequence comprises, in order of 5’ to 3’: a poly-A sequence comprising 30 consecutive adenosine nucleotides, an interrupting linker of 10 nucleotides, and a further poly-A sequence comprising 70 consecutive adenosine nucleotides. In one example, the 3’ tailing sequence comprises, in order of 5’ to 3’: a poly-A sequence comprising 30 consecutive adenosine nucleotides, an interrupting linker comprising or consisting of the nucleotide sequence set forth in SEQ ID NO: 20, and a further poly-A sequence comprising 70 consecutive adenosine nucleotides. In one example, the RNA further comprises a 5’ terminal cap structure. In one example, the 5’ terminal cap structure is an endogenous cap or analogue thereof. For example, the 5’terminal cap structure is an endogenous cap. For example, the 5’terminal cap structure is an analogue of an endogenous cap. In one example, the 5’ terminal cap structure comprise a guanine or guanine analogue thereof. For example, the 5’ terminal cap structure comprise a guanine. For example, the 5’ terminal cap structure comprise a guanine analogue of a guanine. In one example, the 5’ terminal cap structure is selected from a group consisting of anti-reverse cap analogue (ARCA), N7,2'-0-dimethyl-guanosine (mCAP), inosine, N1-methyl-guanosine, 2′fluoro-guanosine, 7-deaza-guanosine, 8-oxo-guanosine, 2- amino-guanosine, LNA-guanosine, 2-azido-guanosine, N6,2'-O-dimethyladenosine, 7- methylguanosine (m7G), Cap1, and Cap2. For example, the 5’ terminal cap structure is anti-reverse cap analogue (ARCA). For example, the 5’ terminal cap structure is N7,2'- 0-dimethyl-guanosine (mCAP). For example, the 5’ terminal cap structure is inosine. For example, the 5’ terminal cap structure is N1-methyl-guanosine. For example, the 5’ terminal cap structure is 2′fluoro-guanosine. For example, the 5’ terminal cap structure is 7-deaza-guanosine. For example, the 5’ terminal cap structure is 8-oxo-guanosine. For example, the 5’ terminal cap structure is 2-amino-guanosine. For example, the 5’ terminal cap structure is LNA-guanosine. For example, the 5’ terminal cap structure is 2-azido-guanosine. For example, the 5’ terminal cap structure is N6,2'-O- dimethyladenosine. For example, the 5’ terminal cap structure is 7-methylguanosine (m7G). For example, the 5’ terminal cap structure is Cap1. For example, the 5’ terminal cap structure is Cap2. In one example, the 5’terminal cap structure is linked to the 5’ end of the RNA by a 5′-5′-triphosphate linkage or a 5’-5’ phosphorothioate linkage. For example, the 5’terminal cap structure is linked to the 5’ end of the RNA by a 5′-5′-triphosphate linkage. For example, the 5’terminal cap structure is linked to the 5’ end of the RNA by a 5’-5’ phosphorothioate linkage. In one example, the self-replicating RNA is from an alphavirus. For example, the alphavirus is selected from the group consisting of Semliki Forest virus (SFV), Sindbis virus (SIN), and Venezuelan equine encephalitis virus (VEE) and combinations thereof. In one example, the self-replicating RNA is from a Semliki Forest virus (SFV). In one example, the self-replicating RNA is from a Sindbis virus (SIN). In one example, the self-replicating RNA is from a Venezuelan equine encephalitis virus (VEE). In one example, the self-replicating RNA comprises or consists of a polynucleotide sequence according to SEQ ID NO: 30. In one example, the antigen is selected from the group consisting of a respiratory syncytial virus (RSV), an influenza virus and / or a SARS-CoV-2. In an example, the antigen is from a respiratory syncytial virus (RSV). In an example, the antigen is from influenza. In an example, the antigen is from a SARS-CoV-2. In one example, the antigens are from a single strain of an influenza virus (i.e., monovalent) or from multiple strains (i.e., multivalent). For example, the immunogenic composition includes antigens from one or more (e.g., 1 or 2 or 3) influenza virus strains. In one example, the composition comprises first and second influenza viral antigens from different strains of the influenza virus. In an example, the composition comprises first, second and third influenza viral antigens from different strains of the influenza virus. For example, the composition comprises (i) a RNA comprising a nucleotide sequence encoding a first influenza antigen; and (ii) a polypeptide antigen from a different strain of influenza. In another example, the composition comprises (i) a RNA comprising a nucleotide sequence encoding a first influenza antigen; (ii) a RNA comprising a nucleotide sequence encoding a second influenza antigen and (iii) a polypeptide of a third influenza antigen. In another example, the composition comprises (i) a RNA comprising a nucleotide sequence encoding a first influenza antigen from influenza A; (ii) a RNA comprising a nucleotide sequence encoding a second influenza antigen from influenza B and (iii) a polypeptide of a third influenza antigen from influenza C. In one example, the antigens are from an influenza A virus strain. For example, the antigens are an influenza A virus hemagglutinin (HA) protein, a neuraminidase (NA) protein, a matrix (M) protein, a nucleoprotein (NP), a non-structural (NS) protein, or an immunogenic fragment or variant thereof. In one example, the antigens are an influenza A hemagglutinin (HA) subtype H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15 or H16 and / or an influenza A neuraminidase (NA) subtype N1, N2, N3, N4, N5, N6, N7, N8 or N9 and / or an influenza A matrix (M) protein subtype M1 or M2 and / or an influenza A non-structural (NS) protein subtype NS1 or NS2. In one example, the influenza viral antigens are from different subtypes of the influenza virus. For example, different hemagglutinin subtypes and / or different neuraminidase subtypes and / or matrix protein subtypes, and / or nucleoprotein subtypes and / or non-structural protein subtypes. The skilled person will be aware that pandemic strains of the influenza virus are commonly H1, H2, H3, H5, H6, H7 or H9 subtype influenza A virus strains. For example, H1N1, H2N2, H3N2, H5N1, H5N3, H6N1, H7N2, H7N3, H7N7, H7N9 and H9N2, strains. In one example, the antigen is a H1N1 antigen from a A / Delaware / 55 / 2019 virus strain. In one example, the antigen is a H1 antigen from a A / Delaware / 55 / 2019 virus strain. In one example, the antigens are from influenza A virus strains having the same hemagglutinin subtypes. In another example, the antigens are influenza A virus strains having different hemagglutinin subtypes. In one example, the antigens are H1, H2, H3, H5, H6, H7 or H9 subtype influenza A virus strains. For example, the antigens are a H1 hemagglutinin, or a H2 hemagglutinin, or a H3 hemagglutinin, or a H5 hemagglutinin, or a H6 hemagglutinin, or a H7 hemagglutinin or a H9 hemagglutinin. For example, the antigens are a H5 subtype influenza A virus strain (i.e., a H5 hemagglutinin). In one example, the H5 hemagglutinin is an A / turkey / Turkey / 1 / 2005 virus strain. In one example, the H3 hemagglutinin is an A / Delaware / 39 / 2019 virus strain In one example, the antigens are influenza A virus strains having the same neuraminidase subtypes. In another example, the antigens are influenza A virus strains having different neuraminidase subtypes. In one example, the antigens are N1, N2, N3, N7 or N9 subtype influenza A virus strains. For example, the antigens are a N1 neuraminidase, or a N2 neuraminidase, or a N3 neuraminidase, or a N7 neuraminidase, or a N9 neuraminidase. For example, the antigens are a N1 neuraminidase subtype influenza A virus strain. In one example, the N1 neuraminidase is an A / turkey / Turkey / 1 / 2005 strain. In one example, the N2 neuraminidase is an A / Delaware / 39 / 2019 virus strain. In one example, the antigens are a H5 hemagglutinin protein and / or a N1 neuraminidase protein. For example, the first antigen is a H5 hemagglutinin subtype influenza A virus strain and the second antigen is a N1 neuraminidase subtype influenza A virus strain. In one example, the antigens are an influenza B virus strain. The skilled person will be aware that influenza B viruses are not divided into subtypes but are classified into two lineages, namely, B / Yamagata and B / Victoria. In one example, the antigens are a B / Yamagata influenza B virus strain. For example, the influenza B virus strain is a B / Singapore / INFTT 160610 / 16 (By) virus strain. In another example, the antigens are a B / Victoria influenza B virus strain. In one example, the antigens are influenza B virus strains in the same lineage. In another example, the antigens are influenza B virus strains in different lineages. In one example, the antigens are an influenza B virus Hyam protein and / or a Nyam protein. For example, antigens are an influenza B virus Hyam protein. In another example, the antigens are an influenza B virus Nyam protein. In a further example, the antigens are an influenza B virus Hyam and Nyam protein. In one example, the antigen is a H1N1 antigen from influenza A and is encodedby a sequence that is at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90% at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% or 100% identical to SEQ ID NO: 5. In another example, the antigen is a H5N1 antigen from influenza A and is encoded by a sequence that is at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90% at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% or 100% identical to SEQ ID NO: 7. In one example, the antigen is a H1N1 antigen from influenza A and has an amino acid sequence that is at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90% at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% or 100% identical to SEQ ID NO: 6. In another example, the antigen is a H5N1 antigen from influenza A and has an amino acid sequence that is at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90% at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% or 100% identical to SEQ ID NO: 8. In one example, the antigen is from influenza B. In one example, the antigen is from influenza C. In one example, the antigens are from a single strain of a SARS-CoV-2 (i.e., monovalent) or from multiple strains of a SARS-CoV-2 (i.e., multivalent). For example, the immunogenic composition includes antigens from one or more (e.g., 1 or 2 or 3) SARS-CoV-2 strains. In one example, the composition comprises first and second SARS-CoV-2 antigens from different strains of a SARS-CoV-2. In an example, the composition comprises first, second and third SARS-CoV-2 antigens from different strains of a SARS-CoV-2 virus. For example, the composition comprises (i) a RNA comprising a nucleotide sequence encoding a first SARS-CoV-2 antigen; and (ii) a polypeptide antigen from a different strain of a SARS-CoV-2. In another example, the composition comprises (i) a RNA comprising a nucleotide sequence encoding a first SARS-CoV-2 antigen; (ii) a RNA comprising a nucleotide sequence encoding a second SARS-CoV-2 antigen and (iii) a polypeptide of a third SARS-CoV-2 antigen. In another example, the composition comprises (i) a RNA comprising a nucleotide sequence encoding a first SARS-CoV-2 antigen from a delta strain of SARS-CoV-2; (ii) a RNA comprising a nucleotide sequence encoding a second SARS-CoV-2 antigen from an Omicron strain of SARS-CoV-2 and (iii) a polypeptide of a third SARS-CoV-2 antigen from a Wuhan (original) strain of SARS-CoV-2. In yet another example, the antigens are from one or more of the Alpha (B.1.1.7) strain, the Beta (B.1.351) strain, the Gamma (P1) strain, the Epsilon (B.1.429) strain, the Delta (B.1.617.2) mutant, the Kappa (B.1.617.1) mutant, the Wuhan (original) strain and / or the Omicron (B.1.1.529) strain of a SARS-CoV-2. In one example, the antigens are a spike (S) protein and / or a nucleocapsid (N) protein of a SARS-CoV-2. For example, the antigens are a SARS-CoV-2 N protein and / or a S protein from the Alpha (B.1.1.7) strain, the Beta (B.1.351) strain, the Gamma (P1) strain, the Epsilon (B.1.429) strain, the Delta (B.1.617.2) mutant, the Kappa (B.1.617.1) mutant, the Wuhan (original) strain and / or the Omicron (B.1.1.529) strain. In one example, the antigens are a SARS-CoV-2 N protein and / or a S protein from the Wuhan (original) SARS-CoV-2 strain. In one example, the antigens are a SARS-CoV-2 N protein and / or a S protein from the delta SARS-CoV-2 strain. In one example, the antigens are a SARS-CoV-2 N protein and / or a S protein from the delta SARS-CoV-2 Omicron strain. In one example, the antigen is a SARS-CoV-2 N protein. In another example, the antigen is an ectodomain of the S protein from the Omicron strain of SARS-CoV-2. For example, the antigen is an ectodomain of the S protein of a SARS-CoV-2 encoded by a sequence that is at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90% at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% or 100% identical to the sequence set forth in SEQ ID NO: 9 or 11. In another example, the antigen is an ectodomain of the S protein of a SARS- CoV-2 spike protein has a sequence that is at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90% at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% or 100% identical to the sequence set forth in SEQ ID NO: 10 or 12. In another example, the S protein is a mutant S protein. In one example, a mutant S protein comprises a mutation in the receptor binding domain. For example, the mutation is selected from the group consisting of S438F, N439K, N440K, L441I, K444R, V445A, V445I, G446V, G446S, N450K, L452R, L452P, L455F, K458N, N460T, D467V, I468F, I468T, I468V, E471O, I472V, A475V, G476S, S477G, S477I, S477N, S477R, T478I, P479L, P479L, P479S, N481D, N481H, V483F, V483A, E484D, E484K, E484K, E484O, G485S, Y489H, Y489D, Y489F, Y489C, Y489N, F490L, F490S, P491R, Q493L, S494P, Y495N, T500N, N501S and Y505H, Y508H. In one example, a mutant S protein comprises a mutation in the receptor binding domain selected from the group consisting of N439K, N439L, L452R, S477N, T478I, V483A and E484D. In one example, a mutant S protein comprises a mutation in the receptor binding domain. For example, the mutation is selected from the group consisting of R346K, K417N, K417T, S438F, N439K, N440K, L441I, K444R, V445A, V445I, G446V, G446S, N450K, L452R, L452P, L455F, K458N, N460T, D467V, I468F, I468T, I468V, E471O, I472V, A475V, G476S, S477G, S477I, S477N, S477R, T478I, T478K, P479L, P479S, N481D, N481H, V483F, V483A, E484D, E484K, E484K, E484O, G485S, Y489H, Y489D, Y489F, Y489C, Y489N, F490L, F490S, P491R, Q493L, S494P, Y495N, T500N, N501S, N501Y, Y505H and Y508H. In one example, a mutant S protein comprises a mutation in the receptor binding domain selected from the group consisting of R346K, K417N, K417T, N439K, N439L, L452R, S477N, T478I, V483A, E484D, E484K and N501Y. In one example, a mutant S protein comprises a mutation selected from the group consisting of P337S, F338L, F338C, G339D, E340K, V341I, A344S, T345S, R346K, A348S, A348T, W353R, N354D, N354K, N354S, S359N, D364Y, V367F, S373L, V382L, P384L, P384S, T385A, T393P, V395I, F400C, R403K, R403S, D405V, R408I, Q414E, Q414K, Q414P, Q414R, T415S, K417R, K417N, I418V, Y421S, Y423C, Y423F, Y423S, D427Y, R509K, V510L, V511E, V512L, L518I, H519O, A520S, A520V, P521R, P521S, A522P, A522S and D614G. In one example, a mutant S protein comprises a mutation selected from the group consisting of L18F, D80A, T95I, Y144S, Y145N, D215G, P337S, F338L, F338C, G339D, E340K, V341I, A344S, T345S, R346K, A348S, A348T, W353R, N354D, N354K, N354S, S359N, D364Y, V367F, S373L, V382L, P384L, P384S, T385A, T393P, V395I, F400C, R403K, R403S, D405V, R408I, Q414E, Q414K, Q414P, Q414R, T415S, K417N, K417T, K417R, I418V, Y421S, Y423C, Y423F, Y423S, D427Y, S438F, N439K, N440K, L441I, K444R, V445A, V445I, G446V, G446S, N450K, L452R, L452P, L455F, K458N, N460T, D467V, I468F, I468T, I468V, E471O, I472V, A475V, G476S, S477G, S477I, S477N, S477R, T478I, T478K, P479L, P479S, N481D, N481H, V483F, V483A, E484D, E484K, E484K, E484O, G485S, Y489H, Y489D, Y489F, Y489C, Y489N, F490L, F490S, P491R, Q493L, S494P, Y495N, T500N, N501S, N501Y, Y505H, Y508H, R509K, V510L, V511E, V512L, L518I, H519O, A520S, A520V, P521R, P521S, A522P, A522S, A570D, D614G, P680H, P681H, A701V, T716I and D950N. In one example, the S protein lacks a furin cleavage site at the the S1 / S2 boundary and / or the S2’ site. In one example, the mutant S protein comprises mutations (e.g., substitutions) that stabilize the S protein in a prefusion conformation. For example, the S protein comprises substitutions K986P and V987P. In one example, the antigens are from a single strain of a respiratory syncytial virus (RSV) (i.e., monovalent) or from multiple strains (i.e., multivalent) of a RSV. For example, the immunogenic composition includes antigens from one or more (e.g., 1 or 2 or 3) RSV strains. In one example, the composition comprises first and second RSV antigens from different strains of RSV. In an example, the composition comprises first, second and third RSV antigens from different strains of RSV. For example, the composition comprises (i) a RNA comprising a nucleotide sequence encoding a first RSV antigen; and (ii) a polypeptide antigen from a different strain of RSV. In another example, the composition comprises (i) a RNA comprising a nucleotide sequence encoding a first RSV antigen; (ii) a RNA comprising a nucleotide sequence encoding a second RSV antigen and (iii) a polypeptide of a third RSV antigen from RSV. For example, the antigen is selected from a RSV surface glycoprotein including a Fusion (F), Glycoprotein (G), Small Hydrophobic protein (SH), the matrix proteins M and M2, the nucleocapsid proteins N, P and L, and the nonstructural proteins NS1 and NS2. In certain examples, the first and second antigens are each an RSV-F antigen. In certain examples, the first, second and third antigens are each an RSV-F antigen. In one example, the antigen is from a Pre F protein of a RSV encoded by a sequence that is at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90% at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% or 100% identical to SEQ ID NO: 1 or 3. In one example, the antigen is from a Pre F protein of a RSV has a sequence that is at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90% at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% or 100% identical to SEQ ID NO: 2 or 4. In one example, the antigen is from a G protein of a RSV. In an example, the composition further comprises one or more additional antigens. In some examples, the composition will therefore comprise a third antigen. In another example, the composition will comprise a fourth antigen. In an example, the one or more additional, or third or fourth antigens are are viral antigens. For example, the viral antigen is from a respiratory virus. In one example, the respiratory virus is selected from the group consisting of influenza virus, respiratory syncytial virus, parainfluenza viruses, metapneumovirus, rhinovirus, coronaviruses, adenoviruses and bocaviruses. In one example, the one or more additional viral antigens are from an influenza virus. In one example, the one or more additional viral antigens are from a respiratory syncytial virus. In one example, the one or more additional viral antigens are from a parainfluenza virus. In one example, the one or more additional viral antigens are from a metapneumovirus. In one example, the one or more additional viral antigens are from a rhinovirus. In one example, the one or more additional viral antigens are from a coronavirus. In one example, the one or more additional viral antigens are from an adenovirus. In one example, the one or more additional viral antigens are from a bocavirus. In one example, the one or more additional antigens are viral antigens from an influenza virus or a coronavirus. In one example, the first, second, third and / or fourth antigens are expressed at substantially the same level. For example, the antigens have a level of expression within about 10%, or about 5% or about 1% of each other. In another example, the first, second, third and / or fourth antigens are expressed at different levels. For example, the antigens have a level of expression greater than about 10%, or about 15% or about 20% of each other. Methods for determining the level of expression are known in the art and / or are described herein. The present disclosure also provides a pharmaceutical composition comprising an immunogenic composition of the present disclosure and a pharmaceutically acceptable carrier. Pharmaceutically acceptable carriers suitable for use in the present disclosure will be apparent to the skilled person and / or are described herein. In one example, the pharmaceutical composition further comprises a lipid nanoparticle (LNP), a polymeric microparticle, and an oil-in-water emulsion. For example, the polynucleotide, the RNA, the cRNA or the self-replicating RNA is encapsulated in, bound to or adsorbed on a LNP, a polymeric microparticle, and an oil- in-water emulsion. In one example, the polynucleotide is encapsulated in, bound to or adsorbed on a LNP, a polymeric microparticle, and an oil-in-water emulsion. In another example, the RNA is encapsulated in, bound to or adsorbed on a LNP, a polymeric microparticle, and an oil-in-water emulsion. For example, the cRNA is encapsulated in, bound to or adsorbed on a LNP, a polymeric microparticle, and an oil-in-water emulsion. For example, the self-replicating RNA is encapsulated in, bound to or adsorbed on a LNP, a polymeric microparticle, and an oil-in-water emulsion. In one example, the pharmaceutical composition further comprises a LNP. For example, the polynucleotide is encapsulated in a LNP. In another example, the RNA is encapsulated in a LNP. For example, the cRNA is encapsulated in a LNP. For example, the self-replicating RNA is encapsulated in a LNP. For example, the polynucleotide is bound to a LNP. In another example, the RNA is bound to a LNP. For example, the cRNA is bound to a LNP. In another example, the self-replicating RNA is bound to a LNP. For example, the polynucleotide is adsorbed on to a LNP. In another example, the RNA is adsorbed on to a LNP. For example, the cRNA is adsorbed on to a LNP. In a further example, the self-replicating RNA is adsorbed on to a LNP. In another example, wherein each RNA is formulated together in the LNP. In another example, wherein each RNA is formulated separately in the LNP. In one example, where multiple RNAs are contemplated, the RNAs are contained within the same LNP. In another example, the multiple RNAs are contained within different LNPs. In one example, the composition further comprises an additional RNA encoding: (i) one or more antigens; (ii) one or more immunopotentiating agents; (iii) one or more chemoattractants; and / or (iv) one or more targeting molecules. In one example, the additional RNA is contained within the same LNP as the RNA encoding the antigen or is contained within a LNP separate to the RNA encoding the antigen. In one example, the LNP comprises a PEG-lipid, a structural lipid and / or a neutral lipid. For example, the LNP comprises a PEG-lipid, a structural lipid and a neutral lipid. In another example, the LNP comprises a PEG-lipid, a structural lipid or a neutral lipid. In one example, the LNP further comprises a cationic lipid. In another example, the LNP does not comprise a cationic lipid. In one example, the pharmaceutical composition further comprises a polymeric microparticle. For example, the polynucleotide is encapsulated in a polymeric microparticle. In another example, the RNA is encapsulated in a polymeric microparticle. For example, the cRNA is encapsulated in a polymeric microparticle. For example, the self-replicating RNA is encapsulated in a polymeric microparticle. For example, the polynucleotide is bound to a polymeric microparticle. In another example, the RNA is bound to a polymeric microparticle. For example, the cRNA is bound to a polymeric microparticle. In another example, the self-replicating RNA is bound to a polymeric microparticle. For example, the polynucleotide is adsorbed on to a polymeric microparticle. In another example, the RNA is adsorbed on to a polymeric microparticle. For example, the cRNA is adsorbed on to a polymeric microparticle. In a further example, the self-replicating RNA is adsorbed on to a polymeric microparticle. In one example, the pharmaceutical composition further comprises an oil-in-water emulsion. For example, the polynucleotide is encapsulated in an oil-in-water emulsion. In another example, the RNA is encapsulated in an oil-in-water emulsion. For example, the cRNA is encapsulated in an oil-in-water emulsion. For example, the self-replicating RNA is encapsulated in an oil-in-water emulsion. For example, the polynucleotide is bound to an oil-in-water emulsion. In another example, the RNA is bound to an oil-in- water emulsion. For example, the cRNA is bound to an oil-in-water emulsion. In another example, the self-replicating RNA is bound to an oil-in-water emulsion. In a further example, the self-replicating RNA is adsorbed on to an oil-in-water emulsion. In a further example, the self-replicating RNA is resuspended in an oil-in-water emulsion. The present disclosure also provides an immunogenic composition or a pharmaceutical composition of the disclosure for use as a vaccine. In one example, the polynucleotide is DNA. In one example, the DNA encodes a cRNA described herein. In one example, the DNA encodes a self-replicating RNA vaccine described herein. In one example, the DNA is a plasmid. The present disclosure provides a method of treating or preventing or delaying progression of a disease or condition in a subject, the method comprising administering the immunogenic composition or the pharmaceutical composition of the present disclosure to a subject in need thereof. In one example, the disclosure provides a method of treating a disease or condition in a subject, the method comprising administering the immunogenic composition or the pharmaceutical composition of the present disclosure to a subject in need thereof. In another example, the disclosure provides a method of preventing a disease or condition in a subject, the method comprising administering the immunogenic composition or the pharmaceutical composition of the present disclosure to a subject in need thereof. In a further example, the disclosure provides a method of delaying progression of a disease or condition in a subject, the method comprising administering the immunogenic composition or the pharmaceutical composition of the present disclosure to a subject in need thereof. In one example, the subject suffers from a disease or condition. In one example, the subject has been diagnosed as suffering from a disease or condition. In one example, the subject is receiving treatment for a disease or condition. In one example, the disease or condition is selected from the group consisting of influenza, COVID-19, a SARS-CoV-2, respiratory syncytial virus (RSV) and acute respiratory distress syndrome (ARDS) or a combination thereof. In another example, the disease or condition is influenza and COVID-19. In another example, the disease or condition is influenza and RSV. In another example, the disease or condition is RSV and COVID-19. In another example, the disease or condition is influenza, RSV and COVID- 19. In another example, the disease or condition is influenza and a SARS-CoV-2. In another example, the disease or condition is a SARS-CoV-2 and RSV. In another example, the disease or condition is a SARS-CoV-2. In another example, the disease or condition is a RSV. In another example, the disease or condition is influenza. In another example, the disease or condition is COVID-19. In another example, the disease or condition is ARDS. A skilled person will understand that where the treatment, prevention or delaying progression of influenza is contemplated, the immunogenic compositions described herein will include at least one polynucleotide comprising a nucleotide sequence encoding an antigen from influenza or an antigen polypeptide from influenza. The composition may comprise additional polynucleotide or polypeptide antigens, for instance from RSV or a SARS-CoV-2, as described herein. In an example, an immunogenic composition suitable for the treatment, prevention or delaying progression of influenza comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of influenza comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of influenza comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of influenza comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of influenza comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of influenza comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a SARS-CoV-2. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of influenza comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of influenza comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of influenza comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of influenza comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a SARS-CoV-2; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of influenza comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a SARS-CoV-2; and (iii) an antigen polypeptide from influenza. A skilled person will understand that where the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19 is contemplated, the immunogenic compositions described herein will include at least one polynucleotide comprising a nucleotide sequence encoding an antigen from a SARS-CoV-2 or an antigen polypeptide from a SARS-CoV-2. The composition may comprise additional polynucleotide or polypeptide antigens, for instance from influenza or a RSV, as described herein. In an example, an immunogenic composition suitable for the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19 comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19 comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19 comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a SARS-CoV-2. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19 comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a SARS-CoV-2; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of a SARS-CoV-2 infection or COVID-19 comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a SARS-CoV-2; and (iii) an antigen polypeptide from influenza. A skilled person will understand that where the treatment, prevention or delaying progression of RSV is contemplated, the immunogenic compositions described herein will include at least one polynucleotide comprising a nucleotide sequence encoding an antigen from a RSV or an antigen polypeptide from a RSV. The composition may comprise additional polynucleotide or polypeptide antigens, for instance from influenza or a SARS-CoV-2, as described herein. In an example, an immunogenic composition suitable for the treatment, prevention or delaying progression of RSV comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from RSV. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of RSV comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from RSV, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of RSV comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from RSV, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from RSV. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of RSV comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of RSV comprises: a) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of RSV comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a SARS-CoV-2. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of RSV comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of RSV comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of RSV comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of RSV comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a SARS-CoV-2; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, an immunogenic composition suitable for the treatment, prevention or delaying progression of RSV comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a SARS-CoV-2; and (iii) an antigen polypeptide from influenza. The present disclosure provides a method of treating or preventing or delaying progression of a disease or condition in a subject, the method comprising locally co- administering (i) a polynucleotide comprising a nucleotide sequence encoding an antigen selected from the group consisting of a respiratory syncytial virus (RSV), influenza and a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (ii) an antigen polypeptide selected from the group consisting of a RSV, influenza and a SARS-CoV-2. In one example, the subject suffers from a disease or condition. In one example, the subject has been diagnosed as suffering from a disease or condition. In one example, the subject is receiving treatment for a disease or condition. In another example, the method is for prophylaxis, e.g., to prevent or reduce the risk of contracting a diseae or condition. In one example, the disease or condition is selected from the group consisting of influenza, COVID-19, a SARS-CoV-2, respiratory syncytial virus (RSV) and acute respiratory distress syndrome (ARDS) or a combination thereof. In another example, the disease or condition is influenza and COVID-19. In another example, the disease or condition is influenza and RSV. In another example, the disease or condition is RSV and COVID-19. In another example, the disease or condition is influenza, RSV and COVID- 19. In another example, the disease or condition is influenza and a SARS-CoV-2. In another example, the disease or condition is a SARS-CoV-2 and RSV. In another example, the disease or condition is a SARS-CoV-2. In another example, the disease or condition is a RSV. In another example, the disease or condition is influenza. In another example, the disease or condition is COVID-19. In another example, the disease or condition is ARDS. A skilled person will understand that where the treatment, prevention or delaying progression of influenza is contemplated, the method described herein will include administering at least one polynucleotide comprising a nucleotide sequence encoding an antigen from influenza or an antigen polypeptide from influenza. The composition may comprise additional polynucleotide or polypeptide antigens, for instance from RSV or a SARS-CoV-2, as described herein. In an example, a method for the treatment, prevention or delaying progression of an infection comprises locally co-adminsering: a) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the method comprises administering: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2. In another example, the method comprises administering: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the method comprises administering: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the method comprises administering: a) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza. In another example, the method comprises administering: (i) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a SARS-CoV-2. In another example, the method comprises administering: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In another example, the method comprises administering: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from influenza. In another example, the method comprises administering: (i) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from influenza; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, the method comprises administering: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a SARS-CoV-2; and (iii) an antigen polypeptide from respiratory syncytial virus (RSV). In another example, the method comprises administering: (i) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) an antigen polypeptide from a SARS-CoV-2; and (iii) an antigen polypeptide from influenza. A skilled person will understand that where the treatment, prevention or delaying progression of a an influenza infection and / or a RSV infection and / or a SARS-CoV-2 infection or COVID-19 is contemplated. Suitable combinations of antigens and / or antigens per se are described herein in relation to immunogenic compositons and shall be taken to apply mutatis mutandis to the methods of treatment described herein. In one example, the disclosure provides a method of treating, preventing or delaying progression of an infection by influenza andor RSV comprising locally co- administering: (i) a F protein from RSV; and (ii) a sa-mRNA encoding a HA from influenza. In one example, the disclosure provides a method of treating, preventing or delaying progression of an infection by influenza andor RSV comprising locally co- administering: (i) a F protein from RSV; and (ii) a sa-mRNA encoding a HA and a NA from influenza. In one example, the disclosure provides a method of treating, preventing or delaying progression of an infection by influenza andor RSV comprising locally co- administering: (i) a F protein from RSV; and (ii) a plurality of sa-mRNAs each sa-mRNA encoding a HA from influenza. In one example, the disclosure provides a method of treating, preventing or delaying progression of an infection by influenza andor RSV comprising locally co- administering: (i) a F protein from RSV; and (ii) a plurality of sa-mRNAs each sa-mRNA encoding a HA and a NA from influenza. In one example, the disclosure provides a method of treating, preventing or delaying progression of an infection by influenza andor RSV comprising locally co- administering: (i) a F protein from RSV; and (ii) three or more sa-mRNAs each sa-mRNA encoding a HA from influenza. In one example, the disclosure provides a method of treating, preventing or delaying progression of an infection by influenza andor RSV comprising locally co- administering: (i) a F protein from RSV; and (ii) three or more sa-mRNAs each sa-mRNA encoding a HA and a NA from influenza. (i) a F protein from RSV; and (ii) four or more sa-mRNAs each sa-mRNA encoding a HA from influenza. In one example, the disclosure provides a method of treating, preventing or delaying progression of an infection by influenza andor RSV comprising locally co- administering: (i) a F protein from RSV; and (ii) four or more sa-mRNAs each sa-mRNA encoding a HA and a NA from influenza. In an example, the present disclosure provides a method of inducing an immune response in a subject, the method comprising administering a pharmaceutical composition disclosed herein, an immunogenic composition disclosed herein or a vaccine disclosed herein to a subject in need thereof or performing a method described herein. In an example, the present disclosure provides use of a pharmaceutical composition disclosed herein, an immunogenic composition disclosed herein or a vaccine disclosed herein in the manufacture of a medicament for inducing an immune response in a subject in need thereof. In an example, the present disclosure provides a pharmaceutical composition disclosed herein, an immunogenic composition disclosed herein or a vaccine disclosed herein for use in inducing an immune response in a subject in need thereof. In one example, the composition or method of the disclosure induces a humoral immune response in the subject. For example, the humoral immune response is an antibody-mediated immune response. For example, production of neutralizing antibodies. In another example, the composition induces a cell-mediated immune response. For example, the cell-mediated immune response includes activation of antigen-specific cytotoxic T cells. For example, the T cells are CD4 T cells and / or CD8 T cells. In one example, the T cells are CD4 T cells. In another example, the T cells are CD8 T cells. In a further example, the T cells are CD4 and CD8 T cells. In one example, administration of a pharmaceutical composition disclosed herein, an immunogenic composition disclosed herein or a vaccine of the present disclosure induces a CD4 T cell mediated immune response. In one example, administration of a pharmaceutical composition, an immunogenic composition disclosed herein or a vaccine of the present disclosure induces a CD8 T cell mediated immune response. In one example, administration of a pharmaceutical composition disclosed herein, an immunogenic composition disclosed herein or a vaccine of the present disclosure induces a CD4 and a CD8 T cell mediated immune response. In one example, the CD4 T cell mediated immune response is a Th0, a Th1 and / or a Th2 response. For example, the CD4 T cell mediated immune response is a Th0 response. In another example, the CD4 T cell mediated immune response is a Th1 response. In a further example, the CD4 T cell mediated immune response is a Th2 response. In one example, the CD4 T cell mediated immune response is a Th0 and Th1 response. In another example, the CD4 T cell mediated immune response is a Th0 and Th2 response. In a further example, the CD4 T cell mediated immune response is a Th1 and Th2 response. In another example, the CD4 T cell mediated immune response is a Th0, Th1 and Th2 response. In one example, the CD8 T cell mediated immune response is a Th0, a Th1 and / or a Th2 response. For example, the CD8 T cell mediated immune response is a Th0 response. In another example, the CD8 T cell mediated immune response is a Th1 response. In a further example, the CD8 T cell mediated immune response is a Th2 response. In one example, the CD8 T cell mediated immune response is a Th0 and Th1 response. In another example, the CD8 T cell mediated immune response is a Th0 and Th2 response. In a further example, the CD8 T cell mediated immune response is a Th1 and Th2 response. In another example, the CD8 T cell mediated immune response is a Th0, Th1 and Th2 response. In one example, the compositions described herein are capable of modifying the Th2:Th1 ratio. In one example, the compositions described herein decrease the Th2:Th1 ratio. In one example, the Th0 response cytokines express interleukin 2 (IL2+) and / or tumor necrosis factor alpha (TNFa+); and / or are negative for interferon gamma (IFNg-), IL5- and / or IL13-. For example, the cytokine is IL2+. In another example, the cytokine is TNFa+. In one example, the cytokine is IFNg-. In another example, the cytokine is IL5-. In a further example, the cytokine is IL13-. In one example, the Th1 response cytokines express interferon gamma (IFNg+); and / or are negative for IL5- and / or IL13-. For example, the cytokine is IFNg+. In another example, the cytokine is IL5-. In a further example, the cytokine is IL13-. In one example, the Th2 response cytokines express IL5+ and / or IL13+; and / or are negative for IFNg. For example, the cytokine is IL5+. In a further example, the cytokine is IL13+. For example, the cytokine is IFNg-. In an example, the present disclosure provides a method for inducing a Th1 immune response in a subject in need thereof, comprising administering a pharmaceutical composition disclosed herein, an immunogenic composition disclosed herein or a vaccine disclosed herein to the subject or performing a method described herein. In an example, the present disclosure provides use of a pharmaceutical composition disclosed herein, an immunogenic composition disclosed herein or a vaccine disclosed herein in the preparation of a medicament for inducing a Th1 immune response in a subject. In an example, the present disclosure provides a pharmaceutical composition disclosed herein, an immunogenic composition disclosed herein or a vaccine disclosed herein for use in inducing a Th1 immune response in a subject. In an example, the present disclosure provides a method for reducing viral load in a subject having a viral infection comprising administering a pharmaceutical composition disclosed herein, an immunogenic composition disclosed herein or a vaccine disclosed herein to a subject having a viral infection or performing a method described herein. In an example, the present disclosure provides use of a pharmaceutical composition disclosed herein, an immunogenic composition disclosed herein or a vaccine disclosed herein in the preparation of a medicament for reducing viral load in a subject having a viral infection. In an example, the present disclosure provides a pharmaceutical composition disclosed herein, an immunogenic composition disclosed herein or a vaccine disclosed herein for use in reducing viral load in a subject having a viral infection. In an example, the subject is a human of 18 years of age or older. In another example, the subject is a human of any age, e.g., from about 1 month to 100 years old, e.g., from about 2 months to about 80 years old, from about 6 months of age to about 3 years old, from about 3 years to about 18 years old, from about 12 years to about 18 years old, from about 18 years to about 55 years old, from about 50 years to about 75 years old, from about 40 years to about 65 years old. In another example, the subject is a human from 2 years of age. In another example, subject is a human from 18 years of age, a human from 30 years of age, a human from 40 years of age, a human from 50 years of age, a human from 60 years of age, a human from 70 years of age, a human from 80 years of age or a human from about 90 years of age. In another example, the subject is less than 2 years of age, less than 18 months of age, less than 12 months of age, less than 6 months of age or less than 3 months of age. In an example, the immunogenic compositions described herein are administered to an infant subject. In an example, the infant subject has, or is suspected of having RSV, influenza and / or a SARS-CoV-2 infection. In an example, the infant is between about 1 month and 12 months of age, or between 2 months and 11 months of age, or between 3 months and 10 months of age, or between 4 months and 9 months of age, or between 5 months and 8 months of age or between 6 months and 7 months of age. In an example, the infant is between about 1 month and 11 months of age, between about 1 month and 10 months of age, between about 1 month and 9 months of age, between about 1 month and 8 months of age, between about 1 month and 7 months of age, between about 1 month and 6 months of age, between about 1 month and 5 months of age, between about 1 month and 4 months of age, between about 1 month and 3 months of age or between about 1 month and 2 months of age. In another example the infant is about 1 month of age, about 2 months of age, about 3 months of age, about 4 months of age, about 5 months of age, about 6 months of age, about 7 months of age, about 8 months of age, about 9 months of age, about 10 months of age, about 11 months of age or about 12 months of age. Thus, in an example, there is provided a method of treating, preventing or delaying progress of a respiratory syncytial virus (RSV) in an infant comprising administering an immunogenic composition, pharmaceutical composition or vaccine disclosed herein to the infant or performing a method described herein. In another example, there is provided use of an immunogenic composition, pharmaceutical composition or vaccine disclosed herein in the preparation of a medicament for treating, preventing or delaying progress of a respiratory syncytial virus (RSV) in an infant. In another example, there is provided an immunogenic composition, pharmaceutical composition or vaccine disclosed herein for use in treating, preventing or delaying progress of a respiratory syncytial virus (RSV) in an infant. In another example, there is provided a method of inducing an immune reponse to a respiratory syncytial virus (RSV) in an infant comprising administering an immunogenic composition, pharmaceutical composition or vaccine disclosed herein to the infant or performing a method described herein. In another example, there is provided use of an immunogenic composition, pharmaceutical composition or vaccine disclosed herein in the preparation of a medicament for inducing an immune reponse to a respiratory syncytial virus (RSV) in an infant. In another example, there is provided an immunogenic composition, pharmaceutical composition or vaccine disclosed herein for use in inducing an immune reponse to a respiratory syncytial virus (RSV) in an infant. Where treatment, prevention or delaying progression of RSV in an infant is contemplated, a skilled person will be aware of suitable immunogenic compositions described herein for administration to the infant. In an example, the immunogenic composition suitable for administration to an infant comprises at least one polynucleotide comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV) and / or an antigen polypeptide from a RSV. The composition may comprise additional polynucleotide or polypeptide antigens, for instance from influenza or a SARS-CoV-2, as described herein. In an example, an immunogenic composition suitable for treatment of RSV in infant comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from a respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; and (ii) an antigen polypeptide selected from the group consisting of a RSV, an influenza virus and / or a SARS-CoV-2. In another example, an immunogenic composition suitable for treatment of RSV in infant comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen selected from the group consisting of a RSV, an influenza virus and / or a SARS-CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and (ii) an antigen polypeptide selected from a RSV. In another example, an immunogenic composition suitable for treatment of RSV in infant comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from respiratory syncytial virus (RSV), wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen selected from the goup consisting of RSV, influenza or SARS-CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide selected from the goup consisting of RSV, influenza or SARS-CoV-2. In another example, an immunogenic composition suitable for treatment of RSV in infant comprises: (i) a RNA comprising a nucleotide sequence encoding an antigen from influenza or SARS-CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; (ii) a RNA comprising a nucleotide sequence encoding an antigen from influenza or SARS-CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and (iii) an antigen polypeptide from a respiratory syncytial virus (RSV). In one example, the immunogenic composition comprises: (i) a F protein from RSV; and (ii) a sa-mRNA encoding a HA from influenza. In one example, the immunogenic composition comprises: (i) a F protein from RSV; and (ii) a sa-mRNA encoding a HA and a NA from influenza. In one example, the immunogenic composition comprises: (i) a F protein from RSV; and (ii) a plurality of sa-mRNAs each sa-mRNA encoding a HA from influenza. In one example, the immunogenic composition comprises: (i) a F protein from RSV; and (ii) a plurality of sa-mRNAs each sa-mRNA encoding a HA and a NA from influenza. In one example, the immunogenic composition comprises: (i) a F protein from RSV; and (ii) three or more sa-mRNAs each sa-mRNA encoding a HA from influenza. In one example, the immunogenic composition comprises: (i) a F protein from RSV; and (ii) three or more sa-mRNAs each sa-mRNA encoding a HA and a NA from influenza. (i) a F protein from RSV; and (ii) four or more sa-mRNAs each sa-mRNA encoding a HA from influenza. In one example, the immunogenic composition comprises: (i) a F protein from RSV; and (ii) four or more sa-mRNAs each sa-mRNA encoding a HA and a NA from influenza. In an example, a composition or vaccine described herein is administered in a one dose regimen. In another example, the composition is administered in a two, three or four dose regimen, wherein the doses are administered about 1, 2 or 3 months apart. The present disclosure also provides a polynucleotide that encodes a self- replicating RNA described herein. For example, the polynucleotide is a recombinant DNA. In one example, the recombinant DNA is a plasmid. In one example, the plasmid comprises a sequence set forth in SEQ ID NO: 31. The present disclosure also provides a kit comprising at least one immunogenic composition of the disclosure, optionally in a delivery system and / or a pharmaceutically acceptable carrier or diluent, packaged with instructions for use in treating or preventing or delaying progression of a disease or disorder in a subject. The present disclosure also provides a kit comprising at least one immunogenic composition of the disclosure, optionally in a delivery system and / or a pharmaceutically acceptable carrier or diluent, packaged with instructions to administer the immunogenic composition to a subject who is suffering from, or at risk of suffering from, a disease or disorder. In one example, an immunogenic composition, a pharmaceutical composition of the disclosure or a vaccine of the disclosure is supplied in a vial. In another example, an immunogenic composition, a pharmaceutical composition of the disclosure or a vaccine of the disclosure is supplied in a syringe. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims. BRIEF DESCRIPTION OF FIGURES Figure 1A. Effect of sa-mRNA on adjuvanted protein vaccine MN and HAI neutralising titers. MN titers were determined by fluorescent foci assay (FFA) microneutralisation test on MDCK cells. GMT titers represent the EC50 values from a non-linear regression with 95% confidence interval. B. Effect of sa-mRNA on adjuvanted protein vaccine IgG titers. IgG titers were determined by Indirect ELISA against Monobulk-H1N1: A / Delaware / 55 / 2019. The geometric mean of the titers for each group are displayed. C. Dose effect of sa-mRNA on IgG subclass. IgG1 and IgG2a titers were determined by Indirect ELISA against Monobulk-H1N1: A / Delaware / 55 / 2019. The geometric mean of the titers for each group are displayed. D. Effect of sa-mRNA on IgG1:IgG2 ratio. Figure 2A. Effect of sa-mRNA on CD4 T-cell cytokines at day 42 in BALB / c mice. B. Effect of sa-mRNA on CD8 T-cell cytokines at day 42 in BALB / c mice. Peptide A is IYSTVASSL influenza A hemagglutinin epitope ID 29690. Figure 3A. Effect of sa-mRNA on adjuvanted protein vaccine MN neutralising titers. B. Effect of sa-mRNA on adjuvanted protein vaccine IgG titers. C. Dose effect of sa-mRNA on IgG subclass. D. Effect of sa-mRNA on IgG1:IgG2a ratio. Figure 4A. Effect of sa-mRNA on the Th response. B. Effect of sa-mRNA on CD4 T cell responses C. Effect of sa-mRNA on CD8 T cell responses. D. Effect of sa-mRNA on T helper cell response. Figure 5A. Effect of sa-mRNA on influenza MN, NA and IgG titers. B. Effect of sa- mRNA on influenza IgG1 and IgG2a responses C. Effect of sa-mRNA on omicron MN titers and ACE2 binding. D. Effect of sa-mRNA on omicron IgG1 and IgG2a responses. Figure 6A. Effect of sa-mRNA and protein based vaccine on CD4 T cell responses. B. Effect of sa-mRNA on T helper cell response. The ratio was set to 50 is zero Th1 cells were detected. The ratios for S protein were excluded if no / low responses were detected. C. Effect of sa-mRNA on CD8 T cell response. Figure 7A. Effect of sa-mRNA and protein based vaccine on H1N1 specific IgG response. B. Effect of sa-mRNA on IgG subclass C. Effect of sa-mRNA on H1N1 HAI titer. D. Effect of sa-mRNA on H1N1 MN titer. E. Effect of sa-mRNA on N1H1 NAI titer Figure 8A. Effect of sa-mRNA and protein based vaccine in presence of LNP adjuvant on neutralising titer. B. Effect of sa-mRNA and protein based vaccine in presence of LNP adjuvant on Pre F specific IgG1 response. C. Effect of sa-mRNA and protein based vaccine in presence of LNP adjuvant on Pre F specific IgG2a response. D-E. Effect of sa-mRNA and protein based vaccine in presence of LNP adjuvant on Pre F specific IgG1:IgG2a ratio. F. Effect of sa-mRNA and protein based vaccine in presence of LNP adjuvant on neutralising titer. Figure 9A. Effect of sa-mRNA and protein based vaccine on the Th1 response. Figure 10A. Effect of sa-mRNA on H1N1 HAI, FFA and IgG titers. B-C. Effect of sa- mRNA on B subunit antibody response. Figure 11A. Effect of sa-mRNA on the nSP1 Th1 response. B. Effect of sa-mRNA on the H1 Th1 response. C. Effect of sa-mRNA on the B / Yamagata Th2 response. D. Ratio of Th2 / Th1 bias by antigen. Figure 12 includes a series of Figures. Figure 12A. Depicts a study design to examine co-formulation and local or distal co-administration of sa-mRNA and unadjuvanted or adjuvanted protein vaccines. Figures 12B-D. Effect of unadjuvanted or adjuvanted protein on sa-mRNA vaccine neutralizing antibody response in context of co- formulation, local co-administration and distal co-administration was determined by influenza HAI, NAI and FFA-based MN assays. Figures 12E. Effect of sa-mRNA on unadjuvanted or adjuvanted protein vaccine neutralizing antibody response in context of co-formulation, local co-administration and distal co-administration was determined by RSV FFA-based MN assay. Figures 12F-G. Effect of co-formulation and local or distal co-administration on IgG subclass response was measured by influenza- or RSV-binding IgG1 and IgG2a ELISA and data shown as a ratio of the antigen-specific IgG1 to IgG2a titers. KEY TO SEQUENCE LISTING DETAILED DESCRIPTION General Throughout this specification, unless specifically stated otherwise or the context requires otherwise, reference to a single step, composition of matter, group of steps or group of compositions of matter shall be taken to encompass one and a plurality (i.e. one or more) of those steps, compositions of matter, groups of steps or groups of compositions of matter. Those skilled in the art will appreciate that the present disclosure is susceptible to variations and modifications other than those specifically described. It is to be understood that the disclosure includes all such variations and modifications. The disclosure also includes all of the steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations or any two or more of said steps or features. The present disclosure is not to be limited in scope by the specific examples described herein, which are intended for the purpose of exemplification only. Functionally-equivalent products, compositions and methods are clearly within the scope of the present disclosure. Any example of the present disclosure herein shall be taken to apply mutatis mutandis to any other example of the disclosure unless specifically stated otherwise. Stated another way, any specific example of the present disclosure may be combined with any other specific example of the disclosure (except where mutually exclusive). Any example of the present disclosure disclosing a specific feature or group of features or method or method steps will be taken to provide explicit support for disclaiming the specific feature or group of features or method or method steps. Unless specifically defined otherwise, all technical and scientific terms used herein shall be taken to have the same meaning as commonly understood by one of ordinary skill in the art (for example, in cell culture, molecular genetics, immunology, immunohistochemistry, protein chemistry, and biochemistry). Unless otherwise indicated, the recombinant protein, cell culture, and immunological techniques utilized in the present disclosure are standard procedures, well known to those skilled in the art. Such techniques are described and explained throughout the literature in sources such as, J. Perbal, A Practical Guide to Molecular Cloning, John Wiley and Sons (1984), J. Sambrook et al. Molecular Cloning: A Laboratory Manual, Cold Spring Harbour Laboratory Press (1989), T.A. Brown (editor), Essential Molecular Biology: A Practical Approach, Volumes 1 and 2, IRL Press (1991), D.M. Glover and B.D. Hames (editors), DNA Cloning: A Practical Approach, Volumes 1-4, IRL Press (1995 and 1996), and F.M. Ausubel et al. (editors), Current Protocols in Molecular Biology, Greene Pub. Associates and Wiley-Interscience (1988, including all updates until present), Ed Harlow and David Lane (editors) Antibodies: A Laboratory Manual, Cold Spring Harbour Laboratory, (1988), and J.E. Coligan et al. (editors) Current Protocols in Immunology, John Wiley & Sons (including all updates until present). The term “and / or”, e.g., “X and / or Y” shall be understood to mean either “X and Y” or “X or Y” and shall be taken to provide explicit support for both meanings or for either meaning. Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. As used herein the term “derived from” shall be taken to indicate that a specified integer may be obtained from a particular source albeit not necessarily directly from that source. Similarly, the term “based on” shall be taken to indicate that a specified integer may be developed or used from a particular source albeit not necessarily directly from that source. Selected Definitions As used herein, the term “self-replicating RNA” refers to a construct based on an RNA virus that has been engineered to allow expression of heterologous RNA and proteins. Self-replicating RNA (e.g., in the form of naked RNA) can amplify in host cells leading to expression of the desired gene product in the host cell. As used herein, the term “conventional mRNA” or “cRNA” or “non-amplifying RNA” refers to a construct that allows expression of heterologous RNA and proteins but the RNA that cannot amplify in host cells. As used herein, the term “monocistronic” in reference to the self-replicating RNA, refers to a RNA that encodes one polypeptide. As used herein, the term “multicistronic” (also known as “polycistronic”) in reference to the polynucleotide, RNA, cRNA and / or self-replicating RNA, refers to a RNA that encodes two or more polypeptides. The term encompasses “bicistronic” (or “dicistronic”; i.e., encoding two polypeptides), “tricistronic” (i.e., encoding three polypeptides) molecules as well as RNA that is capable of encoding more than three polypeptides. By “bicistronic” is meant a single nucleic acid that is capable of encoding two distinct polypeptides from different regions of the nucleic acid. The term “naked” as used herein refers to nucleic acids that are substantially free of other macromolecules, such as lipids, polymers and proteins. A “naked” nucleic acid, such as a self-replicating RNA, is not formulated with other macromolecules to improve cellular uptake. Accordingly, a naked nucleic acid is not encapsulated in, absorbed on, or bound to a LNP, a liposome, a polymeric microparticle or an oil-in-water emulsion. As used herein, the term “nucleotide sequence” or “nucleic acid sequence” will be understood to mean a series of contiguous nucleotides (or bases) covalently linked to a phosphodiester backbone. By convention, sequences are presented from the 5' end to the 3' end, unless otherwise specified. To facilitate a clear description of the nucleic acids, particular sequence components are referred to as e.g., a “first nucleotide sequence” and a “second nucleotide sequence”. It is to be understood that the first and second sequences can appear in any desired order or orientation, unless otherwise specified, and that no particular order or orientation is intended by the words “first”, “second” etc. As used herein, the term “antigen” refers to a molecule or structure containing one or more epitopes that induce, elicit, augment or boost a cellular and / or humoral immune response. Antigens can include, for example, proteins and peptides from a pathogen such as a virus, bacteria, fungus, protozoan, plant or from a tumour. The term “polypeptide” or “polypeptide chain” will be understood to mean a series of contiguous amino acids linked by peptide bonds. For example, a protein shall be taken to include a single polypeptide chain i.e., a series of contiguous amino acids linked by peptide bonds or a series of polypeptide chains covalently or non-covalently linked to one another (i.e., a polypeptide complex). The series of polypeptide chains can be covalently linked using a suitable chemical or a disulfide bond. Examples of non- covalent bonds include hydrogen bonds, ionic bonds, Van der Waals forces, and hydrophobic interactions. As used herein, the term “operably linked to” means positioning a subgenomic promoter or regulatory element (e.g., an IRES) relative to a nucleic acid such that expression of the nucleic acid is controlled or regulated by the element. For example, a subgenomic promoter can be operably linked to numerous nucleic acids, e.g., through another regulatory element, such as an internal ribosome entry site (IRES). As used herein, the term “subgenomic promoter” (also known as ‘junction region’ promoter) refers to a promoter that directs the expression of a heterologous nucleotide sequence, regulating protein expression. As used herein, the term “internal ribosome entry site” or “IRES” refers to a sequence of nucleotides within a mRNA to which a ribosome or a component thereof, e.g., a 40S subunit of a ribosome, is capable of binding. An IRES need not necessarily comprise nucleic acid that induces translation of a mRNA (e.g., a start codon; AUG). The term “recombinant” shall be understood to mean the product of artificial genetic recombination. As used herein, the terms “disease”, “disorder” or “condition” refers to a disruption of or interference with normal function, and is not to be limited to any specific condition, and will include diseases or disorders. As used herein, a subject “at risk” of developing a disease or condition may or may not have detectable disease or symptoms of disease, and may or may not have displayed detectable disease or symptoms of disease prior to the treatment according to the present disclosure. “At risk” denotes that a subject has one or more risk factors, which are measurable parameters that correlate with development of the disease or condition, as known in the art and / or described herein. As used herein, the terms “treating”, “treat” or “treatment” include administering a RNA or composition described herein to thereby reduce or eliminate at least one symptom of a specified disease or condition. As used herein, the term “preventing”, “prevent” or “prevention” includes providing prophylaxis with respect to occurrence or recurrence of a specified disease or condition in an individual. An individual may be predisposed to or at risk of developing the disease but has not yet been diagnosed with the disease. As used herein, the phrase “delaying progression of” includes reducing or slowing down the progression of the disease or condition in an individual and / or at least one symptom of a disease or condition. An “effective amount” refers to at least an amount effective, at dosages and for periods of time necessary, to achieve the desired result. For example, the desired result may be a therapeutic or prophylactic result. An effective amount can be provided in one or more administrations. In some examples of the present disclosure, the term “effective amount” is meant an amou...

Claims

CLAIMS 1. An immunogenic composition comprising: a) a RNA comprising a nucleotide sequence encoding an antigen selected from the group consisting of a respiratory syncytial virus (RSV), an influenza virus and a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide selected from the group consisting of a RSV, an influenza virus and a SARS-CoV-2.

2. The immunogenic composition of claim 1, comprising: a) a RNA comprising a nucleotide sequence encoding an antigen from a RSV, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2.

3. The immunogenic composition of claim 1, comprising: a) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a RSV.

4. The immunogenic composition of claim 1, comprising: a) a RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza.

5. The immunogenic composition of claim 1, comprising: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a SARS-CoV-2.

6. The immunogenic composition of claim 1, comprising: a) a RNA comprising a nucleotide sequence encoding an antigen from influenza, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from a RSV.

7. The immunogenic composition of claim 1, comprising:a) a RNA comprising a nucleotide sequence encoding an antigen from a RSV, wherein the nucleotide sequence is operably linked to a regulatory element; and b) an antigen polypeptide from influenza.

8. The immunogenic composition of claim 1, further comprising a second RNA comprising a nucleotide sequence encoding an antigen selected from the group consisting of a RSV, an influenza virus and a SARS-CoV-2, wherein the nucleotide sequence is operably linked to a regulatory element.

9. The immunogenic composition of claim 1, further comprising a second antigen polypeptide selected from the group consisting of a RSV, an influenza virus and a SARS- CoV-2.

10. The immunogenic composition of claim 2 or 3, further comprising a second RNA comprising a nucleotide sequence encoding an antigen from influenza, operably linked to a regulatory element.

11. The immunogenic composition of claim 10, comprising, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from RSV or SARS-CoV-2; (ii) the RNA comprising a nucleotide sequence encoding an antigen from influenza.

12. The immunogenic composition of claim 10, comprising, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from influenza; and (ii) the RNA comprising a nucleotide sequence encoding an antigen from RSV or SARS-CoV-2.

13. The immunogenic composition of claim 2 or 3, further comprising a second antigen polypeptide from influenza.

14. The immunogenic composition of claim 4 or 5, further comprising a second RNA comprising a nucleotide sequence encoding an antigen from a RSV, operably linked to a regulatory element.

15. The immunogenic composition of 14, comprising, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2; (ii) the RNA comprising a nucleotide sequence encoding an antigen from RSV.

16. The immunogenic composition of 14, comprising, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from RSV; and (ii) the RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2.

17. The immunogenic composition of claim 4 or 5, further comprising a second antigen polypeptide from a RSV.

18. The immunogenic composition of claim 6 or 7, further comprising a second RNA comprising a nucleotide sequence encoding an antigen from a SARS-CoV-2, operably linked to a regulatory element.

19. The immunogenic composition of claim 18, comprising, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2; (ii) the RNA comprising a nucleotide sequence encoding an antigen from influenza.

20. The immunogenic composition of claim 18, comprising, in order from 5’ to 3’: (i) the RNA comprising a nucleotide sequence encoding an antigen from influenza; and (ii) the RNA comprising a nucleotide sequence encoding an antigen from a SARS- CoV-2.

21. The immunogenic composition of claim 6 or 7, further comprising a second antigen polypeptide from a SARS-CoV-2.

22. The immunogenic composition of any one of claims 8, 10 to 12, 14 to 16 or 18 to 20, comprising a plurality of RNAs, wherein each self-replicating RNA encodes different polypeptide sequences.

23. The immunogenic composition of any one of claims 1 to 22, wherein the regulatory element is selected from the group consisting of a promoter, an internal ribosome entry site (IRES) or a Kozak consensus sequence or a combination thereof.

24. The immunogenic composition of claim 23, wherein the promoter is a subgenomic (SG) promoter.

25. The immunogenic composition of claim 24, wherein the SG promoter is a minimal SG promoter.

26. The immunogenic composition of claim 24, wherein the SG promoter is extended SG promoter.

27. The immunogenic composition of claim 25, wherein the minimal SG promoter is encoded by a sequence set forth in SEQ ID NO:

13.

28. The immunogenic composition of claim 26, wherein the extended SG promoter is encoded by a sequence set forth in SEQ ID NO:

14.

29. The immunogenic composition of claim 23, wherein the nucleotide sequence encoding an antigen is operably linked to an IRES located 5’ to the nucleotide sequence encoding the antigen.

30. The immunogenic composition of claim 23 or 29, wherein the IRES is an IRES from encephalomyocarditis virus (EMCV), poliovirus (PV), human enterovirus, foot- and-mouth disease virus (FMDV), hepatitis C virus (HCV), classical swine fever virus (CSFV), murine leukemia virus (MLV), simian immunodeficiency virus (SIV), Eukaryotic translation initiation factor 4G (elF4G), Death-associated protein 5 (DAP5), cellular Myc (c-Myc), NF-κB-repressing factor (NRF), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF-2), platelet-derived growth factor B (PDGF B), Antennapedia, X-linked inhibitor of apoptosis (XIAP or Apaf-1), immunoglobulin heavy-chain binding protein BiP, or fibroblast growth factor 1a (FGF1A), GTX, or a combination thereof.

31. The immunogenic composition of claim 30, wherein the EMCV IRES is a wild- type IRES encoded by a sequence set forth in SEQ ID NO:

16.

32. The immunogenic composition of any one of claims 1, 2, 7, 8, 11, 12 or 14 to 16, wherein the nucleotide sequence encoding an antigen from a RSV has a sequence at least 70%, at least 75%, at least 80%, at least 85%, at least 90% or at least 95% identical to SEQ ID NO:1 or 3.

33. The immunogenic composition of any one of claims wherein the nucleotide sequence encoding an antigen from a RSV has the sequence set forth in SEQ ID NO:1 or 3.

34. The immunogenic composition of any one of claims 1, 3, 4, 8, 12, 15, 16, 18, 19 or 20, wherein the nucleotide sequence encoding an antigen from a SARS-CoV-2 has a sequence at least 70%, at least 75%, at least 80%, at least 85%, at least 90% or at least 95% identical to SEQ ID NO: 9 or 11.

35. The immunogenic composition of any one of claims 1, 3, 4, 8, 12, 15, 16 or 18 to 20, wherein the nucleotide sequence encoding an antigen from a SARS-CoV-2 has the sequence set forth in SEQ ID NO: 9 or 11.

36. The immunogenic composition of any one of claims 1, 5, 6, 8, 10 to 12, 19 or 20, wherein the nucleotide sequence encoding an antigen from influenza has a sequence at least 70%, at least 75%, at least 80%, at least 85%, at least 90% or at least 95% identical to SEQ ID NO: 5 or 7.

37. The immunogenic composition of any one of claims 1, 5, 6, 8, 10 to 12, 19 or 20, wherein the nucleotide sequence encoding an antigen from influenza has the sequence set forth in SEQ ID NO: 5 or 7.

38. The immunogenic composition of any one of claims 1, 3, 6, 9 or 17, wherein the antigen polypeptide from a RSV has an amino acid sequence at least 70%, at least 75%, at least 80%, at least 85%, at least 90% or at least 95% identical to SEQ ID NO: 2 or 4.

39. The immunogenic composition of any one of claims 1, 3, 6, 9 or 17, wherein the antigen polypeptide from a RSV has the amino acid sequence set forth in SEQ ID NO: 2 or 4.

40. The immunogenic composition of any one of claims 1, 2, 5, 9 or 21, wherein the antigen polypeptide from a SARS-CoV-2 has an amino acid sequence at least 70%, at least 75%, at least 80%, at least 85%, at least 90% or at least 95% identical to SEQ ID NO: 10 or 12.

41. The immunogenic composition of any one of claims 1, 2, 5, 9 or 21, wherein the antigen polypeptide from a SARS-CoV-2 has the amino acid sequence set forth in SEQ ID NO: 10 or 12.

42. The immunogenic composition of any one of claims 1, 4, 7, 9 or 13, wherein the antigen polypeptide from influenza has an amino acid sequence at least 70%, at least 75%, at least 80%, at least 85%, at least 90% or at least 95% identical to SEQ ID NO: 6 or 8.

43. The immunogenic composition of any one of claims 1, 4, 7, 9 or 13, wherein the antigen polypeptide from influenza has the amino acid sequence set forth in SEQ ID NO: 6 or 8.

44. The immunogenic composition of any one of claims 1 to 43, wherein the RNA is selected from the group consisting of cRNA or a self-replicating RNA.

45. The immunogenic composition of claim 44, wherein the self-replicating RNA is from an alphavirus, optionally selected from the group consisting of Semliki Forest virus (SFV), Sindbis virus (SIN), and Venezuelan equine encephalitis virus (VEE) and combinations thereof.

46. The immunogenic composition of any one of claims 1 to 45, further comprising an adjuvant.

47. The immunogenic composition of claim 46, wherein the adjuvant is MF59.

48. The immunogenic composition of any one of claims 1 to 47, further comprising an additional RNA encoding, or a polypeptide selected from: (i) one or more antigens; (ii) one or more immunopotentiating agents; (iii) one or more chemoattractants; and / or (iv) one or more targeting molecules.

49. A pharmaceutical composition comprising an immunogenic composition of any one of claims 1 to 48 and a pharmaceutically acceptable carrier.

50. The pharmaceutical composition of claim 49, further comprising a lipid nanoparticle (LNP), a polymeric microparticle or an oil-in-water emulsion.

51. The pharmaceutical composition of claim 50, wherein the RNA is encapsulated in, bound to or adsorbed on a LNP, a polymeric microparticle or an oil-in-water emulsion.

52. The pharmaceutical composition of any one of claims 49 to 51, wherein each RNA is formulated together in the LNP.

53. The pharmaceutical composition of any one of claims 49 to 51, wherein each RNA is formulated separately in the LNP.

54. The immunogenic composition of any one of claims 1 to 48 or the pharmaceutical composition of any one of claims 49 to 53, for use as a vaccine.

55. A vaccine comprising the pharmaceutical composition of any one of claims 49 to 53 or the immunogenic composition of any one of claims 1 to 48.

56. A method of treating or preventing or delaying progression of a disease or condition in a subject in need thereof, the method comprising administering the immunogenic composition any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 to the subject.

57. Use of the immunogenic composition any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 inthe manufacture of a medicament for treating or preventing or delaying progression of a disease or condition in a subject in need thereof.

58. The immunogenic composition any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 for use in treating or preventing or delaying progression of a disease or condition in a subject in need thereof.

59. The method of claim 56, the use of claim 57 or the pharmaceutical composition, the immunogenic composition or the vaccine for use of claim 58, wherein the disease or condition is selected from influenza, RSV, a SARS-CoV-2 infection and / or COVID-19.

60. A method of inducing an immune response in a subject, the method comprising administering the immunogenic composition any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 to a subject in need thereof.

61. Use of the immunogenic composition any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 in the manufacture of a medicament for inducing an immune response in a subject in need thereof.

62. The immunogenic composition any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 for use in inducing an immune response in a subject in need thereof.

63. The method of claim 60, the use of claim 61, or the immunogenic composition, the pharmaceutical composition or vaccine for use of claim 62, wherein the immune response is a cell-mediated immune response, optionally a Th2 response.

64. A method for reducing viral load in a subject comprising administering the immunogenic composition any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 to the subject in need thereof.

65. Use of the immunogenic composition any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 in the preparation of a medicament for reducing viral load in a subject in need thereof.

66. The immunogenic composition any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 for use in reducing viral load in a subject in need thereof.

67. A method for inducing a Th1 immune response in a subject in need thereof, comprising administering the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 to the subject.

68. Use of the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 in the preparation of a medicament for inducing a Th1 immune response in a subject.

69. The pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 for use in inducing a Th1 immune response in a subject.

70. The method of any one of claims 56, 59, 60, 63, 64 or 67, the use of any one of claims 57, 59, 61, 63, 65 or 68, or the immunogenic composition, the pharmaceutical composition or vaccine for use of any one of claims 58, 59, 62, 63, 66 or 69, wherein the subject is a human of 18 years of age or older.

71. A method of treating, preventing or delaying progress of a respiratory syncytial virus (RSV) in an infant comprising administering the immunogenic composition of any one of claims 1, 2, 3, 6 to 9, 11, 12 or 14 to 17, or a pharmaceutical composition or vaccine thereof, to the infant.

72. Use of the immunogenic composition of any one of claims 1, 2, 3, 6 to 9, 11, 12 or 14 to 17, or a pharmaceutical composition or vaccine thereof, in the preparation of a medicament for treating, preventing or delaying progress of a respiratory syncytial virus (RSV) in an infant.

73. The immunogenic composition of any one of claims 1, 2, 3, 6 to 9, 11, 12 or 14 to 17, or a pharmaceutical composition or vaccine thereof for use in treating, preventing or delaying progress of a respiratory syncytial virus (RSV) in an infant.

74. A method of inducing an immune response in an infant comprising administering the immunogenic composition of any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 to the infant.

75. Use of the immunogenic composition of any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 in the preparation of a medicament for inducing an immune response in an infant.

76. The immunogenic composition of any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53 or the vaccine of claim 55 for use in inducing an immune response in an infant.

77. The method of claim 74, the use of claim 75, or the pharmaceutical composition, immunogenic composition or vaccine for use of claim 76, wherein the immune response is a cell-mediated immune response, optionally a Th1 response.

78. The method of claim 71, the use of claim 72 or the immunogenic composition, pharmaceutical composition or vaccine for use of claim 73, wherein the infant is between about 1 month and 12 months of age.

79. The method of any one of claims 56, 59, 60, 63, 64, 67, 70, 71, 74 or 77, the use of any one of claims 57, 59, 61, 63, 65, 68, 70, 72, 75, 77 or 78 or the pharmaceutical composition, immunogenic composition or vaccine for use of any one of claims 58, 59, 62, 63, 66, 69, 70, 73, 76 to 78, wherein the vaccine or composition is administered in a one dose regimen.

80. The method of any one of claims 56, 59, 60, 63, 64, 67, 70, 71, 74 or 77, the use of any one of claims 57, 59, 61, 63, 65, 68, 70, 72, 75, 77 or 78 or the pharmaceutical composition, immunogenic composition or vaccine for use of any one of claims 58, 59, 62, 63, 66, 69, 70, 73, 76 to 78, wherein the composition or vaccine is administered in a two, three or four dose regimen, wherein the doses are administered about 1, 2 or 3 months apart.

81. A kit comprising: (a) the immunogenic composition any one of claims 1 to 48, the pharmaceutical composition of any one of claims 49 to 53, or the vaccine of claim 55; (b) instructions for use thereof; and optionally (c) a diluent.

82. A method of treating or preventing or delaying progression of a disease or condition in a subject, the method comprising locally co-administering (i) a polynucleotide comprising a nucleotide sequence encoding an antigen selected from the group consisting of a respiratory syncytial virus (RSV), influenza and a severe acute respiratory syndrome coronavirus (SARS-CoV-2), wherein the nucleotide sequence is operably linked to a regulatory element; and (ii) an antigen polypeptide selected from the group consisting of a RSV, influenza and a SARS-CoV-2.

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