High-dose influenza vaccine for children

Abstract

Disclosed herein are immunogenic compositions and vaccination regimes for immunizing humans against influenza disease.

Description

Technical Field

[0001] This application claims the benefit of priority of U.S. Provisional Application No. 62 / 982,993, filed Feb. 28, 2020, and U.S. Provisional Application No. 63 / 080,931, filed Sep. 21, 2020, the entire contents of each of which are hereby incorporated by reference herein for any purpose.

[0002] This disclosure relates to the field of vaccines and details a study to evaluate the safety and immunogenicity of different doses of quadrivalent influenza vaccine (QIV) in subjects 6 months to less than 18 years of age.

Background Art

[0003] Influenza is an infectious acute viral respiratory disease caused by influenza A and B viruses. Influenza typically features a rapid onset of fever, muscle pain, sore throat and dry cough, and can cause severe malaise lasting for several days. Influenza affects all age groups, but infants and young children are at increased risk of influenza and its complications due to their developing immune systems and lack of previous exposure, and thus lack of immunity. Complications of influenza in the pediatric population include, for example, secondary bacterial pneumonia, acute otitis media, bronchitis, febrile seizures, Reye syndrome, myositis, neurological conditions and exacerbation of underlying conditions (Non-Patent Document 1; Non-Patent Document 2; Non-Patent Document 3).

[0004] Currently, vaccination is the most effective medical intervention against influenza and its severe complications. However, the development of effective influenza vaccines for high-risk groups such as very young (neonatal and pediatric individuals) and very elderly (65 years and older) remains challenging, as these populations exhibit reduced responsiveness to influenza vaccination compared to adults. In older adults, poor vaccine responsiveness may be due to age-related declines in immune function (Non-Patent Literature 4). For example, in older adult populations, reduced B-cell response appears to be a result of both endogenous and exogenous changes, such as far fewer naive B cells, less germinal center response, and attenuation of CD4 helper T cell function (Non-Patent Literature 5; Non-Patent Literature 6). In contrast, inadequate vaccine protection in infants and young children may be due to an immature immune system associated with lower BCR activation, a different cytokine environment during priming (i.e., less Th1-like and more anti-inflammatory), and reduced persistence of long-term viable plasma cells in the bone marrow (Non-Patent Literature 7; Non-Patent Literature 8). A further complicating factor in the development of influenza vaccines for infants and young children is concerns about safety (e.g., increased reactivity, risk of febrile seizures), particularly when the influenza vaccine is administered concurrently with routine childhood vaccines that are standard of care. Due to such safety concerns, for over 30 years, influenza vaccines for children under 3 years of age contained half the amount of antigen (i.e., a 0.25 mL dose containing 7.5 μg HA / strain / dose) instead of the standard dose recommended for older children and adults (i.e., a 0.5 mL dose containing 15 μg HA / strain / dose). This continued until 2019, when the US FDA approved the use of Sanofi Pasteur's 0.5 mL Fluzone® tetravalent standard dose (QIV-SD) vaccine in children aged 6–35 months.

[0005] Therefore, an influenza vaccine with improved safety and efficacy remains urgently needed in infants and young children. Moreover, immunocompromised children are at even higher risk of influenza and its complications, and can benefit from an improved influenza vaccine. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Munoz, FM (2002) Semin. Pediatr. Infect. Dis. Vol. 13 (No. 2): pp. 72-78 [Non-Patent Document 2] Peltola V. et al. (2003) Clin. Infect. Dis. Vol. 36 (No. 3): pp. 299-305 [Non-Patent Document 3] Antonova EN et al. (2012) BMC Public Health Vol. 12: p. 968 [Non-Patent Document 4] Weinberger et al. (2008) Clin. Infect. Dis. Vol. 46 (No. 7): pp. 1078-1084 [Non-Patent Document 5] Crooke SN et al. (2019) Immun Ageing Vol. 16, p. 25 [Non-Patent Document 6] Ciabattini A. et al. (2018) Semin Immunol. Vol. 40: pp. 83-94 [Non-Patent Document 7] Basha S. et al. (2014) Expert Rev Clin Immunol. Vol. 10 (No. 9): pp. 1171-1184 [Non-Patent Document 8] Saso A. et al. (2017) Semin Immunopathol. Vol. 39 (No. 6): pp. 627-642 [Overview of the project] [Means for solving the problem]

[0007] In particular, the following embodiments are provided herein:

[0008] Embodiment 1. A method for immunizing a child against the influenza virus, comprising the step of administering a QIV-HD vaccine to a child between 6 months and under 18 years of age.

[0009] Embodiment 2. A method for immunizing a child subject against the influenza virus, wherein the child subject: a. Approximately 30 μg, 45 μg, or 60 μg of hemagglutinin from H1N1 influenza A virus strain per dose; b. Approximately 30 μg, 45 μg, or 60 μg of hemagglutinin from the H3N2 influenza A virus strain per dose; c. Approximately 30 μg, 45 μg, or 60 μg of hemagglutinin from Yamagata lineage influenza B virus strains per dose; d. Approximately 30 μg, 45 μg, or 60 μg of hemagglutinin from Victoria lineage influenza B virus strains per dose; e. Children must be between 6 months and under 18 years of age. A method comprising the step of administering a QIV-HD vaccine containing [a specific substance].

[0010] Embodiment 3. The method according to Embodiment 1 or 2 for preventing influenza virus infection in children.

[0011] Embodiment 4. The method of Embodiment 1 or 2 for inducing a protective immune response in a child.

[0012] Embodiment 5. The method of Embodiment 4, wherein the immune response is an antibody response.

[0013] Embodiment 6. The method of Embodiment 1 or 2, wherein the vaccine comprises, per dose, approximately 30 μg of hemagglutinin from an H1N1 influenza A virus strain, approximately 30 μg of hemagglutinin from an H3N2 influenza A virus strain, approximately 30 μg of hemagglutinin from a Yamagata lineage influenza B virus strain, and approximately 30 μg of hemagglutinin from a Victoria lineage influenza B virus strain.

[0014] Embodiment 7. The method of Embodiment 1 or 2, wherein the vaccine comprises, per dose, approximately 45 μg of hemagglutinin from an H1N1 influenza A virus strain, approximately 45 μg of hemagglutinin from an H3N2 influenza A virus strain, approximately 45 μg of hemagglutinin from a Yamagata lineage influenza B virus strain, and approximately 45 μg of hemagglutinin from a Victoria lineage influenza B virus strain.

[0015] Embodiment 8. The method of Embodiment 1 or 2, wherein the vaccine comprises, per dose, approximately 60 μg of hemagglutinin from an H1N1 influenza A virus strain, approximately 60 μg of hemagglutinin from an H3N2 influenza A virus strain, approximately 60 μg of hemagglutinin from a Yamagata lineage influenza B virus strain, and approximately 60 μg of hemagglutinin from a Victoria lineage influenza B virus strain.

[0016] Embodiment 9. A method for immunizing a child against the influenza virus, wherein the child is between 6 months and under 18 years of age: a. Approximately 60 μg of hemagglutinin from the H1N1 influenza A virus strain per dose; b. Approximately 60 μg of hemagglutinin from the H3N2 influenza B virus strain per dose; c. Approximately 60 μg of hemagglutinin from the Yamagata lineage influenza B virus strain per dose; d. Approximately 60 μg of hemagglutinin from Victoria lineage influenza B virus strains per dose. A method comprising the step of administering a QIV-HD vaccine comprising

[0017] Embodiment 10. The method of any one of Embodiments 1 to 9, wherein the vaccine is administered intramuscularly.

[0018] Embodiment 11. The pediatric subject is a. 6 months to less than 36 months of age; b. 3 years to less than 5 years old; c. 5 years to less than 9 years old; and / or d. 9 years to less than 18 years old The method of any one of Embodiments 1 to 10.

[0019] Embodiment 12. The method of any one of Embodiments 1 to 11, wherein the pediatric subject is 6 months to less than 24 months of age.

[0020] Embodiment 13. The method of any one of Embodiments 1 to 12, wherein the vaccine is administered to the same subject once or twice. <000010​​​​​​​​​​​​​​​​​​​​​​

[0027] Embodiment 20. The method of Embodiment 19, wherein the subject is administered a single dose of vaccine.

[0028] Embodiment 21. Any one of Embodiments 1 to 20, wherein the administration reduces the incidence of laboratory-confirmed influenza-like illness compared to vaccination of a similar age group using QIV-SD, wherein the confirmed influenza-like illness is characterized by the occurrence of a fever of over 38°C or equal to 38°C for at least 24 hours, as well as at least one of the following: cough, sputum production, wheezing, dyspnea, nasal congestion, rhinorrhea, pharyngitis, otitis media, vomiting, diarrhea, sore throat, chills (shivering), fatigue (malaise), headache, and myalgia (muscle pain).

[0029] Embodiment 22. A method of administration in any one of Embodiments 1 to 21 that reduces the incidence of test-confirmed influenza-like illness caused by a virus type / subtype antigenically similar to that contained in the vaccine composition.

[0030] Embodiment 23. An administration method from any one of Embodiments 1 to 22 that reduces the incidence of acute otitis media (AOM), acute lower respiratory tract infection (ALRI, e.g., pneumonia), hospitalization, and / or drug use.

[0031] Embodiment 24.2 The dose of vaccine is administered to an unvaccinated subject of influenza, and the administration of two doses of vaccine results in a higher geometric mean titer (GMT) for each of the strains used for vaccination compared to vaccination using QIV-SD, one of the methods of Embodiments 1 to 23.

[0032] Embodiment 25. Any one of Embodiments 1 to 24, wherein the administration of the vaccine results in a higher serum neutralized geometric mean titer (GMT) for each of the strains used for vaccination compared to vaccination using QIV-SD.

[0033] Embodiment 26. The administration is one of the methods of Embodiments 1 to 25, which produces a geometric mean HI antibody titer (GMT) ratio (QIV-HD / QIV-SD) higher than the GMT ratio of TIV-HD / TIV-SD in adults aged 65 years or older.

[0034] Embodiment 27. Any one of Embodiments 24 to 26, for children between 6 months and under 3 years of age.

[0035] Embodiment 28. The vaccine is manufactured from bird eggs, according to any one of Embodiments 1 to 27.

[0036] Embodiment 29. Any one of Embodiments 1 to 27, wherein the vaccine is not manufactured from bird eggs.

[0037] Embodiment 30. The vaccine is produced by any one of Embodiments 1 to 27 using recombinant DNA technology.

[0038] Embodiment 31. The vaccine is inactivated or attenuated, according to any one of Embodiments 1 to 27.

[0039] Embodiment 32. The method of Embodiment 31, wherein the vaccine is inactivated.

[0040] Embodiment 33. The method of Embodiment 31, wherein the vaccine is attenuated.

[0041] Embodiment 34. The vaccine is a split virus vaccine, according to any one of Embodiments 1 to 33.

[0042] Embodiment 35. A vaccine comprising an adjuvant, according to any one of Embodiments 1 to 34.

[0043] Embodiment 36. Any one of Embodiments 1 to 34, wherein the vaccine does not contain an adjuvant.

[0044] Embodiment 37. Any one of Embodiments 1 to 36, wherein the subject is an immunocompromised child.

[0045] Embodiment 38. Any one of Embodiments 1 to 37, for which pediatric subjects are at high risk.

[0046] Embodiment 39. Any one of Embodiments 1 to 38, wherein the subject is a child who has or has had asthma, diabetes, heart disease, HIV, AIDS, or cancer.

[0047] Embodiment 40. Any one of Embodiments 1 to 39, wherein the vaccine is safe and well-tolerated in children.

[0048] Further subject matter and advantages are partially described below, partially evident from the description, and partially learned through practice. These subject matter and advantages are realized and achieved using the elements and combinations specifically indicated in the attached claims.

[0049] It should be understood that both the general statements above and the detailed statements below are for illustrative and explanatory purposes only and do not limit the scope of the claims.

[0050] The accompanying drawings incorporated into and forming part of this specification illustrate, along with descriptions, one (or more) embodiments and serve to illustrate the principles described herein. [Brief explanation of the drawing]

[0051] [Figure 1-1] Figures 1A to 1D are schematic diagrams of the first three stages of a clinical trial for subjects under 5 years of age. [Figure 1-2] Continuation of Figure 1-1. [Figure 1-3] Continuation of Figure 1-2. [Figure 2-1] Figures 2A and 2C show schematic diagrams of the first three stages of a clinical trial for subjects aged 5 to 8 years. [Figure 2-2] Continuation of Figure 2-1. [Figure 3]This figure shows a schematic diagram of Stage 1 of the test for subjects aged 9-17. [Figure 4] This figure shows participant trends for a US cohort aged 6 months to under 18 years. [Figure 5] This figure shows that in subjects aged 6 months to under 36 months (who had not been previously vaccinated), two doses of QIV-HD (60 μg) administered one month apart produced a higher geometric mean titer (GMT) than a single dose of QIV-HD (60 μg). QIV-SD is a registered trademark of Fluarix®. The Y-axis represents the geometric mean titer (GMT). [Figure 6-1] Figures 6A–6D show involuntary reported responses for US cohorts aged 6 months to under 3 years (Figure 6A), 3 years to under 5 years (Figure 6B), 5 years to under 9 years (Figure 6C), and 9 years to under 18 years (Figure 6D). Involuntary reported responses were recorded up to 7 days post-vaccination. The percentage of participants with involuntary reported responses after any vaccine administration is presented. Results are relative to the safety analysis set. In this figure and throughout, "IIV4" and "QIV" are used interchangeably. QIV-SD was provided at 15 μg hemagglutinin / strain. [Figure 6-2] Continuation of Figure 6-1. [Figure 7-1] Figures 7A–7E show the geometric mean titer (GMT) at 28 days post-last vaccination for the US cohort. Ages 6 months to under 18 years (Figure 7A); 6 months to under 3 years (Figure 7B); 3 years to under 5 years (Figure 7C); 5 years to under 9 years (Figure 7D); 9 years to under 18 years (Figure 7E). Results are relative to the immunogenicity analysis set. CI, confidence interval. QIV-SD provided at 15 μg hemagglutinin / strain. [Figure 7-2] Continuation of Figure 7-1. [Figure 7-3] Continuation of Figure 7-2. [Figure 8-1]Figures 8A–8E show the geometric mean titer ratio of QIV-HD to QIV-SD 28 days after the last vaccine administration for the US cohort. 6 months to under 18 years (Figure 8A); 6 months to under 3 years (Figure 8B); 3 years to under 5 years (Figure 8C); 5 years to under 9 years (Figure 8D); 9 years to under 18 years (Figure 8E). Results are relative to the immunogenicity analysis set. QIV-SD was provided at 15 μg hemagglutinin / strain. [Figure 8-2] Continuation of Figure 8-1. [Figure 8-3] Continuation of Figure 8-2. [Figure 9-1] Figures 9A–9E show the seroconversion rates at 28 days post-last vaccination for the US cohort. Ages 6 months to under 18 years (Figure 9A); 6 months to under 3 years (Figure 9B); 3 years to under 5 years (Figure 9C); 5 years to under 9 years (Figure 9D); 9 years to under 18 years (Figure 9E). Results are relative to the immunogenicity analysis set. QIV-SD was provided at 15 μg hemagglutinin / strain. [Figure 9-2] Continuation of Figure 9-1. [Figure 9-3] Continuation of Figure 9-2. [Figure 10-1] Figures 10A–10E show the ratios of geometric mean serum neutralizing antibody titers 28 days after the last vaccine dose for a US cohort. The ratios are for day 28 after the last vaccine dose compared to day 0. Age groups: 6 months to under 18 years (Figure 10A); 6 months to under 3 years (Figure 10B); 3 years to under 5 years (Figure 10C); 5 years to under 9 years (Figure 10D); 9 years to under 18 years (Figure 10E). Results are relative to the immunogenicity analysis set. QIV-SD was provided at 15 μg hemagglutinin / strain. [Figure 10-2] Continuation of Figure 10-1. [Figure 10-3] Continuation of Figure 10-2. [Figure 11]Figures 11A and 11B show the involuntary reported responses and grades to vaccine administration in US participants aged 6 months to <3 years after administration 1 (Figure 11A) and administration 2 (Figure 11B). Involuntary reported responses were recorded up to 7 days after vaccination and graded from 1 for mild, 2 for moderate, and 3 for severe (see Tables 20A and 20D). Results are relative to the safety analysis set. QIV-SD was provided at 15 μg hemagglutinin / strain. [Figure 12-1] Figures 12A–12E show involuntary reported responses and grades to vaccine administration in US participants aged 3 to <18 years. Involuntary reported responses were recorded up to 7 days after vaccination and graded from 1 for mild, 2 for moderate, and 3 for severe (see Tables 20A and 20D). Results are relative to the safety analysis set. 3 to under 5 years, administration 1 (Figure 12A); 3 to under 5 years, administration 2 (Figure 12B); 5 to under 9 years, administration 1 (Figure 12C); 5 to under 9 years, administration 2 (Figure 12D); 9 to under 18 years (Figure 12E). [Figure 12-2] Continuation of Figure 12-1. [Figure 12-3] Continuation of Figure 12-2. [Figure 13] Figures 13A and 13B show the geometric mean titers for participants aged 6 months to <3 years at 28 days post-vaccination in a US cohort, categorized by their previous influenza vaccination status (previously vaccinated (Figure 13A) and unvaccinated (Figure 13B)). Results are relative to the immunogenicity analysis set. QIV-SDs were provided at 15 μg hemagglutinin / strain. CI = confidence interval. [Figure 14-1] Figures 14A–14E show the geometric mean post-vaccination / pre-vaccination titer ratios for the US cohort 28 days after the last vaccination. Results are relative to the immunogenicity analysis set. 6 months to under 18 years (Figure 14A); 6 months to under 3 years (Figure 14B); 3 years to under 5 years (Figure 14C); 5 years to under 9 years (Figure 14D); 9 years to under 18 years (Figure 14E). [Figure 14-2] Continuation of Figure 14-1. [Figure 14-3] Continuation of Figure 14-2. [Figure 15] Figures 15A and 15B show involuntary reported responses and grades to vaccine administration in a Canadian cohort. Involuntary reported responses were recorded and graded on the day of each vaccine administration and for 7 days post-vaccination. Results are relative to the safety analysis set. 6 months to under 2 years of age, administration 1 (Figure 15A); 6 months to under 2 years of age, administration 2 (Figure 15B). [Figure 16] Figures 16A and 16B show an overview of safety regarding local reactions in a US cohort of children aged 6 months to under 3 years after the first (Figure 16A) and second (Figure 16B) doses of QIV-HD. No increase in involuntary reported injection site reactions or grade 3 reactions was observed with increasing QIV-HD administration. [Figure 17] Figures 17A and 17B show an overview of the safety of systemic reactions in a US cohort of children aged 6 months to under 3 years after the first (Figure 17A) and second (Figure 17B) doses of QIV-HD. No increase in systemic reactions or grade 3 reactions was observed with increasing QIV-HD administration. [Figure 18] This figure shows the serum neutralizing GMT for a US cohort of children aged 6 months to 3 years using QIV-HD 60 μg. [Modes for carrying out the invention]

[0052] definition Unless otherwise indicated, the following terms and phrases, when used herein, are intended to have the following meanings:

[0053] Where used herein, the term “or any combination thereof” refers to all permutations and combinations of the terms listed prior to the term. For example, “A, B, C or any combination thereof” is intended to include: A, B, C, AB, AC, BC or ABC, and, where the order is important in a particular context, at least one of BA, CA, CB, ACB, CBA, BCA, BAC or CAB. Following this example, combinations containing repetitions of one or more items or terms are also clearly included, such as BB, AAA, AAB, BBC, AAABCCCC, CBBAAA, CABABB, etc. Those skilled in the art will understand that, unless otherwise evident from the context, there is typically no limit to the number of items or terms in any combination.

[0054] "Or" is used with a comprehensive meaning unless the context requires a different interpretation, and is equivalent to "and / or".

[0055] As used herein, “antigen” refers to a factor that elicits an immune response and / or a factor that, when exposed to or administered to an organism, binds to a T cell receptor (e.g., when presented by an MHC molecule) or an antibody (e.g., produced by a B cell). In some embodiments, an antigen elicits a humoral response in an organism (e.g., production of antigen-specific antibodies). Alternatively, or in addition, in some embodiments, an antigen elicits a cellular response in an organism (e.g., involving a T cell whose receptor specifically interacts with the antigen). It will be recognized by those skilled in the art that a particular antigen may elicit an immune response in one or more members of a target organism (e.g., mouse, rabbit, primate, human), but not in all members of the target species. In some embodiments, the antigen elicits an immune response in at least about 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and 99% of members of the target species. In some embodiments, the antigen may or may not bind to antibodies and / or T cell receptors and induce specific physiological responses in the organism. In some embodiments, for example, the antigen can bind to antibodies and / or T cell receptors in vitro, regardless of whether such interactions occur in vivo. In some embodiments, the antigen reacts with specific humoral or cellular immunity products, including those induced by heterologous immunosources. In some embodiments, influenza hemagglutinin (HA) polypeptide or its immunogenic fragments are antigens.

[0056] As used herein, “hemagglutinin” or “HA” protein refers to a membrane-endogenous glycoprotein on the surface of the influenza virus membrane. Specifically, the HA protein is typically expressed on the surface of the influenza virion as a homotrimeric complex. Individual HA monomer polypeptides can be further separated into a distal spherical head region and a proximal stem region. The HA protein is involved in mediating viral attachment and subsequent membrane fusion with target cells. Currently, there are at least 18 known HA subtypes (i.e., H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15, H16, H17, and H18) defined by their interaction with antibodies. Humans are commonly infected with H1, H2, and H3 subtype viruses. In some embodiments, the HA protein can be monomeric and contain a single HA polypeptide. In other embodiments, the HA protein is trimeric and contains three HA polypeptides. As used herein, “hemagglutinin polypeptide” or “HA polypeptide” refers to a polypeptide whose amino acid sequence contains at least one characteristic sequence of HA. HA polypeptides may include full-length influenza HA polypeptide sequences and fragments thereof. Those skilled in the art can generally identify HA polypeptides and / or sequences characteristic of specific HA polypeptides (i.e., H1, H2, or H3 polypeptides) or of HA that mediate infection in specific hosts (e.g., birds, camels, dogs, cats, civets, horses, humans, leopards, minks, mice, seals, stone martins, pigs, tigers, whales, etc.). The National Center for Biotechnology Information (NCBI) maintains a database of HA polypeptide sequences.

[0057] As used herein, "influenza virus" refers to a segmented negative-strand RNA virus belonging to the family Orthomyxoviridae.

[0058] When used herein, “influenza vaccine” refers to an immunogenic composition capable of stimulating an immune response and administered for the prevention, improvement, or treatment of influenza virus infection. Examples of influenza vaccines include, for example, attenuated or dead (e.g., split) influenza viruses, virus-like particles (VLPs) and / or antigenic polypeptides or proteins (e.g., HA polypeptides or trimer HA proteins as described herein) or DNA derived therefrom, or any recombinant versions of such immunogenic materials. Influenza vaccines also include DNA and viral vector-based vaccines. Vaccines as envisioned herein may optionally contain one or more adjuvants.

[0059] As used herein, “immune response” refers to the response of cells of the immune system, such as B cells, T cells, dendritic cells, macrophages, or polymorphonuclear cells, to a stimulus, such as an antigen or vaccine. An immune response may include any cells of the body involved in the host defense response, such as epithelial cells that secrete interferon or cytokines. Immune responses include, but are not limited to, innate and / or adaptive immune responses. As used herein, “protective immune response” refers to an immune response that protects an object from infection (e.g., preventing infection or the development of an infection-related disease). Methods for measuring immune responses are well known in the art and include, for example, by measuring the proliferation and / or activity of lymphocytes (e.g., B or T cells), the secretion of cytokines or chemokines, inflammation, antibody production, etc. “Antibody response” is an immune response in which antibodies are produced.

[0060] As used herein, “prevention” refers to the prevention of disease onset, avoidance of disease symptoms, delay of onset, and / or reduction of the frequency and / or severity of one or more symptoms of a particular disease, disorder, or condition (e.g., influenza virus infection). In some embodiments, prevention is evaluated on a population basis such that a factor is considered to “prevent” a particular disease, disorder, or condition if a statistically significant reduction in the onset, frequency, and / or intensity of one or more symptoms of the disease, disorder, or condition is observed in a population susceptible to the disease, disorder, or condition.

[0061] As used herein, the terms “vaccination” or “to vaccinate” refer to the administration of a composition intended to produce an immune response to a disease-causing factor, for example. Vaccination may be administered before, during, and / or after exposure to a disease-causing factor and / or the onset of one or more symptoms, and in some embodiments, before, during, and / or immediately after exposure to the factor. In some embodiments, vaccination may involve multiple doses of the vaccine composition, appropriately timed apart.

[0062] As used herein, "adjuvant" refers to a substance or vehicle that nonspecifically enhances the immune response to an antigen. Adjuvants may include, without limitation, suspensions of minerals (e.g., alum, aluminum hydroxide, or phosphate) to which the antigen has been adsorbed, or water-in-oil or oil-in-water emulsions in which the antigen solution is emulsified in mineral oil or water (e.g., Freund's incomplete adjuvant). Dead mycobacteria may be included to further enhance antigenicity (e.g., Freund's complete adjuvant). Immunostimulatory oligonucleotides (e.g., CpG motifs) can also be used as adjuvants (see, for example, U.S. Patents 6,194,388; 6,207,646; 6,214,806; 6,218,371; 6,239,116; 6,339,068; 6,406,705; and 6,429,199). Biomolecules, such as Toll-like receptor (TLR) agonists and costimulatory molecules, can also be used as adjuvants. Representative biological adjuvants include, but are not limited to, IL-2, RANTES, GM-CSF, TNF-α, IFN-γ, G-CSF, LFA-3, CD72, B7-1, B7-2, OX-40L, 4-1BBL, or combinations thereof.

[0063] The phrase "pharmaceutically acceptable" refers to molecular entities and compositions that, when administered to mammals, particularly humans, do not produce allergic or similar adverse reactions. Typically, a pharmacopoeia (pharmaceutically acceptable) composition retains the desired biological activity of the parent compound and does not impart any unwanted toxicological effects.

[0064] A serum viral neutralization (SVN) assay (also referred to herein as a serum neutralization assay / test) is a serological test for detecting the presence and scale of functional systemic antibodies that prevent viral infectivity. SVN assays are highly sensitive and specific tests for measuring the titer of neutralizing antibodies pre-infection or post-vaccination. Conventional SVN methods are performed in vitro and are based on the inhibition of viral infectivity in cell culture in the presence of neutralizing antibodies. Titer determination may be based on the presence or absence of cytopathic effects or evidence of viral infection using immunoassay techniques.

[0065] Children may be considered "high risk" if they have one or more of the following conditions: asthma, neurological and / or neurodevelopmental conditions (disorders of the brain, spinal cord, peripheral nerves and muscles, e.g., cerebral palsy, epilepsy (paroxysmal disorder), stroke, intellectual disability (mental retardation), moderate to severe developmental delay, muscular dystrophy or spinal cord injury), chronic lung disease (e.g., cystic fibrosis), heart disease (e.g., congenital heart disease, congestive heart failure and coronary artery disease), blood disorders (e.g., sickle cell anemia), endocrine disorders (e.g., diabetes mellitus), kidney disorders, liver disorders, metabolic disorders (e.g., hereditary metabolic disorders and mitochondrial disorders), weakened immune system due to disease or medication (e.g., HIV or AIDS, children or adolescents with cancer, or children or adolescents using chronic steroids), or taking medications containing aspirin or salicylates. Extreme obesity, which has been associated with severe influenza illness in some adult studies, may also be a risk factor in children. Childhood obesity is defined as a body mass index (BMI) that is at or above the 95th percentile for age and sex.

[0066] The standard dose trivalent influenza vaccine ("TIV-SD") contains 15 micrograms (μg) or less of hemagglutinin (HA) from each of the three virus strains, as recommended by the WHO for use in the next influenza season in its hemisphere, with a total HA antigen of 45 μg or less per dose. TIV-SD contains one HA from the influenza A / H1N1 strain, another HA from the influenza A / H3N2 strain, and one HA from the influenza B Victoria or B Yamagata lineage strain.

[0067] Fluad® is an adjuvant (MF59 in an oil-in-water emulsion of squalane oil) TIV-SD manufactured by Seqirus UK Limited. It is supplied as a 0.25 mL liquid solution containing 7.5 μg of HA for each of the three virus strains recommended by the WHO for use in the next influenza season in its hemisphere at a total of 22.5 μg of HA antigen per dose.

[0068] High-dose trivalent influenza vaccines ("TIV-HD") are similar to TIV-SD in that they contain three types of HA (one from the influenza A / H1N1 strain, another from the influenza A / H3N2 strain, and one from the influenza B Victoria or Yamagata lineage strain), but they differ in that they contain more than 15 μg of HA per strain. A typical TIV-HD can contain, for example, 60 μg of HA from each of the three virus strains (more than four times the amount of antigen in TIV-SD, with a total of 180 μg of HA antigen per dose).

[0069] The representative TIV-HD, Fluzone® high-dose, was developed by Sanofi Pasteur and subsequently approved in the United States, Canada, Australia, Brazil, and the United Kingdom to improve the efficacy of vaccines in adults aged 65 and older (Centers for Disease Control and Prevention. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP), 2009. MMWR. 2009; Vol. 58 (RR-8): pp. 1-52). Fluzone® high-dose is the only influenza vaccine approved in adults aged 65 and older that has shown superior efficacy over the TIV-SD influenza vaccine for laboratory-confirmed influenza-like illness (DiazGranados et al. (2014) NEJM Vol. 371: pp. 635-645).

[0070] TIV-SD and TIV-HD (i.e., trivalent influenza vaccines) contain a single influenza B strain. However, two different genetic lineages of influenza B virus (Victoria and Yamagata lineages) co-epidemic worldwide; both are involved in influenza disease. However, the B strains included in seasonal influenza vaccines were not the dominant epidemic B lineage (mismatched strains) in approximately 25% of the seasons between 2000 and 2013 (Caini S. et al. (2015) Influenza Other Respir. Viruses. Vol. 9 (Appendix 1): pp. 3-12). To overcome the problem of B strain selection and improve population protection against seasonal influenza virus strains, commercially available influenza vaccines have shifted to tetravalent formulations containing additional B strain HA. Therefore, the challenge of having to select a strain from only one B lineage for seasonal influenza vaccines, and the resulting risks imposed by the potential widespread outbreak of alternative B lineage strains, can be resolved by using a tetravalent formulation (Gorse GJ et al. (2015) Vaccine Vol. 33 (No. 9): pp. 1151-1159).

[0071] As used herein, “QIV-SD vaccine” refers to a standard dose quadrivalent influenza vaccine containing 15 μg or less of each of four virus strains recommended by the WHO for use in the next influenza season in its hemisphere, the four strains being: one Victoria lineage influenza B strain, one Yamagata lineage influenza B strain, one H1N1 influenza A strain, and one H3N2 influenza A strain. In some embodiments, QIV-SD contains 15 μg of HA per strain, with a total of 60 μg of HA antigen per dose.

[0072] As described herein, Fluarix® tetravalent is a non-adjuvant QIV-SD manufactured by GlaxoSmithKline (GSK), and is referred to herein as "non-adjuvant QIV-SD".

[0073] As used herein, “QIV-HD vaccine” refers to a high-dose quadrivalent influenza vaccine containing more than 15 μg of HA from each of four virus strains recommended by the WHO for use in the next influenza season in its hemisphere, the four strains being: one Victoria lineage influenza B strain, one Yamagata lineage influenza B strain, one H1N1 influenza A strain, and one H3N2 influenza A strain. In some embodiments, QIV-HD contains 30 μg, 45 μg, or 60 μg of HA per strain, with a total of 120 μg, 180 μg, or 240 μg of HA antigen per dose, respectively.

[0074] In some embodiments, the QIV-HD vaccine can be formulated as a sterile aqueous suspension of inactivated influenza virus for intramuscular (IM) injection, prepared from influenza virus grown in fertilized chicken eggs. In such embodiments, the virus-containing fluid is collected and inactivated with formaldehyde. The influenza virus is concentrated and purified in a solution with a linear sucrose density gradient using a continuous flow centrifuge. The virus can then be chemically disintegrated using the nonionic surfactant octylphenol ethoxylate (Triton® X-100, also named octoxynol-9) to produce a "split virus." Formaldehyde is then added twice to complete the inactivation of the influenza virus and ensure clearance of the avian leukemia virus. Finally, the split virus is further purified by dialysfiltration into phosphate-buffered saline (PBS) solution and then sterile filtered. Antibiotics and preservatives may or may not be used in the method for preparing QIV-HD.

[0075] The following table shows the qualitative and quantitative composition of one representative formulation of QIV-HD vaccine at a dose of 0.7 mL:

[0076] [Table 1]

[0077] Typical vaccine compositions A method for immunizing a pediatric subject against the influenza virus, comprising the step of administering a QIV-HD vaccine, is disclosed herein. In some embodiments, the pediatric subject is between 6 months and under 18 years of age. In some embodiments, the method prevents influenza, and in some embodiments, the method induces a protective immune response in the pediatric subject. In some embodiments, a vaccine composition comprising QIV-HD is provided for use in any one of the methods described herein, for example, to immunize a pediatric subject against the influenza virus. A typical QIV-HD vaccine composition is provided herein for use in any one of the methods disclosed herein.

[0078] Numerous influenza vaccines are currently available and are generally based on either live or inactivated (dead) viruses. In some embodiments, the QIV-HD vaccine is attenuated. In some embodiments, the QIV-HD vaccine contains an inactivated virus. The inactivated vaccine may be based on whole virions, split virions, or purified surface antigens. The influenza antigen may also exist in the form of virosomals. In some embodiments, the QIV-HD vaccine contains a live virus. In some embodiments, the QIV-HD vaccine contains an inactivated virus. In some embodiments, the QIV-HD vaccine contains a whole virion. In some embodiments, the QIV-HD vaccine contains a split virion. In some embodiments, the QIV-HD vaccine contains a purified surface antigen. In some embodiments, the QIV-HD vaccine contains virosomals. In some embodiments, the QIV-HD vaccine contains a split virion that is inactivated.

[0079] Chemical means for inactivating viruses include treatment with one or more of the following factors in an effective amount: surfactants, formaldehyde, β-propiolactone, methylene blue, psoralen, carboxyfullerene (C60), binary ethylamine, acetylethyleneimine, or combinations thereof. Non-chemical methods for virus inactivation are known in the art, such as UV light or gamma ray irradiation.

[0080] Virions can be collected from virus-containing fluids by various methods. For example, the purification process may involve zone centrifugation using a solution with a linear sucrose density gradient containing a surfactant to break down the virions. The antigen is then purified, for example, by diafiltration, after dilution as needed.

[0081] Split virions can be obtained by processing purified virions with surfactants (e.g., ethyl ether, polysorbate 80, deoxycholate, tri-N-butyl phosphate, Triton X-100, Triton N101, cetyltrimethylammonium bromide, Tergitol NP9, etc.) to produce subvirion formulations, and this is well known in the art. In some embodiments, the QIV-HD vaccine contains split virions.

[0082] In some embodiments, the QIV-HD vaccine contains purified surface antigen. In some embodiments, the QIV-HD vaccine contains influenza surface antigen hemagglutinin and optionally neuraminidase. Methods for producing these proteins in purified form are well known in the art. In some embodiments, the QIV-HD vaccine contains purified surface antigen.

[0083] Another form of inactivated influenza antigen is virosomes (virus-like liposome particles that do not contain nucleic acids). Virosomes can be produced by solubilizing the influenza virus with a surfactant, followed by removal of the nucleocapsid and reconstitution of the membrane containing viral glycoproteins. An alternative method for producing virosomes involves adding viral membrane glycoproteins to an excess amount of phospholipids to obtain liposomes with viral proteins in the membrane. In some embodiments, the QIV-HD vaccine is a virosome.

[0084] Stock Selection The representative vaccines of this disclosure contain hemagglutinin from at least two different influenza A virus strains and at least two influenza B virus strains. The strains are based on recommendations from the WHO or the Vaccines and Related Biological Products Advisory Committee (VRBPAC) (USA) for the specific influenza season in question. The strains vary based on seasonal WHO / VRBPAC recommendations. Different strains are typically grown separately, then mixed after the viruses have been harvested and antigens have been produced. The strains used in the vaccines of this disclosure may have natural HA as found in wild-type viruses, or modified HA.

[0085] In some embodiments, the vaccine composition of the Disclosure comprises a reassorted strain of influenza virus. In some embodiments, the reassorted strain is obtained by reverse genetics techniques. In some embodiments, the reassorted strain is not obtained by reverse genetics techniques. Typically, the vaccines disclosed herein comprise an influenza strain that is transmissible from person to person. In some embodiments, the genome of the strain comprises at least one RNA segment originating from a mammalian (e.g., human) influenza virus. In some embodiments, the genome of the strain comprises at least one NS segment originating from an avian influenza virus.

[0086] In some embodiments, the vaccine compositions disclosed herein include strains that may be resistant to antiviral therapy (e.g., resistant to oseltamivir and / or zanamivir), including resistant, widespread strains.

[0087] In some embodiments, the vaccine composition disclosed herein includes a strain that has not been passaged through an egg at any stage between isolation from a patient and replication in a cell culture system. In some embodiments, the vaccine composition disclosed herein includes a strain that has been passaged through an egg. In some embodiments, the egg is from a bird. In some embodiments, the bird egg is from a chicken (e.g., a hen).

[0088] In some embodiments, the vaccine composition disclosed herein comprises hemagglutinin having a binding preference to oligosaccharides having a Sia(α2,6)Gal terminal disaccharide. In some embodiments, the vaccine composition disclosed herein comprises hemagglutinin having a binding preference to oligosaccharides having a Sia(α2,3)Gal terminal disaccharide. Human influenza viruses bind to receptor oligosaccharides having a Sia(α2,6)Gal terminal disaccharide (sialic acid linked to galactose by α-2,6), while egg and Vero cells have receptor oligosaccharides having a Sia(α2,3)Gal terminal disaccharide. The growth of human influenza virus in cells, e.g., MDCK, unlike egg passages, results in selective pressure that maintains the innate Sia(α2,6)Gal binding to hemagglutinin.

[0089] In some embodiments, the vaccine compositions disclosed herein include a glycoprotein (including hemagglutinin) having a glycosylation pattern different from that of a virus derived from an egg, and in such cases, the glycoprotein includes a glycoform not found in chicken eggs.

[0090] Influenza A virus currently exhibits 16 HA subtypes: H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15, and H16. In some embodiments, the vaccine compositions disclosed herein provide protection against one or more of these subtypes. In some embodiments, the vaccine compositions disclosed herein provide protection against one or more of the influenza A virus NA subtypes N1, N2, N3, N4, N5, N6, N7, N8, or N9. In some embodiments, the vaccine compositions disclosed herein include H1 and H3 strains. In some embodiments, the vaccine compositions disclosed herein include three influenza A virus strains, for example, H1, H3, and a widespread epidemic-related strain.

[0091] Characteristics of epidemic-related influenza strains include: (a) containing novel hemagglutinins compared to hemagglutinins in currently circulating human strains, i.e., those that have not been apparent in human populations for decades (e.g., H2) or those that have never been seen in human populations before (e.g., H5, H6, or H9, which were commonly found only in avian populations), such that vaccine recipients and the general human population are immunologically naive to the hemagglutinins of the strain; (b) being capable of horizontal transmission in human populations; and (c) being pathogenic to humans. In some embodiments, the vaccine compositions disclosed herein include epidemic-related influenza virus strains comprising H2, H5, H7, or H9 subtypes (e.g., H5N1, H5N3, H9N2, H2N2, H7N1, or H7N7). The epidemic strain may have an H1 subtype (e.g., H1N1). In some embodiments, the vaccine composition disclosed herein comprises HA from an H1N1 influenza A virus strain and HA from an H3N2 influenza A virus strain.

[0092] Influenza B virus strains emerged in the late 1980s and belong to two distinct lineages with HAs that are antigenically and / or genetically distinguishable from each other. Current influenza B virus strains are either B / victoria / 2 / 87-like or B / yamagata / 16 / 88-like (referred to herein as the "victoria lineage" or the "yamagata lineage," respectively). While these strains are typically antigenically distinct, differences in amino acid sequences are also explained to distinguish the two lineages.

[0093] In some embodiments, the vaccine composition disclosed herein comprises antigens from at least two influenza B virus strains. In some embodiments, the vaccine composition disclosed herein comprises HA from a Yamagata lineage influenza B virus strain and / or HA from a Victoria lineage influenza B virus strain.

[0094] In some embodiments, the vaccine composition disclosed herein comprises HA from the Yamagata lineage influenza B virus strain, HA from the Victoria lineage influenza B virus strain, HA from the H1N1 influenza A virus strain, and HA from the H3N2 influenza A virus strain. In some embodiments, at least two of the influenza B virus strains may have different hemagglutinin-containing but related neuraminidases. For example, both may have a B / Victoria / 2 / 87-like neuraminidase, or both may have a B / Yamagata / 16 / 88-like neuraminidase.

[0095] In some embodiments, the vaccine compositions disclosed herein contain two, three, four, five, six, seven, eight, nine, or ten or more HAs. In some embodiments, the vaccine compositions disclosed herein contain two, three, four, five, six, seven, eight, nine, or ten or more HAs and one or more neuraminidases (NAs).

[0096] Administration Hemagglutinin (HA) is the primary immunizer in current inactivated influenza vaccines, and vaccine doses are typically standardized by reference to HA levels. The QIV-HD vaccine composition for use in the methods disclosed herein contains a “high dose” of HA per strain (compared to the “standard dose”).

[0097] In some embodiments, the QIV-HD vaccine composition contains approximately 30 μg to 60 μg of HA per strain. In some embodiments, the QIV-HD vaccine composition contains approximately 30 μg, 35 μg, 40 μg, 45 μg, 50 μg, 55 μg, or 60 μg of HA per strain. In some embodiments, the QIV-HD vaccine composition contains approximately 30 μg of HA per strain. In some embodiments, the QIV-HD vaccine composition contains approximately 45 μg of HA per strain. In some embodiments, the QIV-HD vaccine composition contains approximately 60 μg of HA per strain. In some embodiments, the QIV-HD vaccine composition contains more than approximately 15 μg of HA per strain. In some embodiments, the QIV-HD vaccine composition contains more than approximately 15 μg of HA per strain, and the amount of HA per strain in μg differs among the four types of HA (e.g., 30 μg of HA for one strain and 45 μg of HA for another strain).

[0098] In some embodiments, the QIV-HD vaccine composition contains approximately 30 μg of HA per strain per dose in volumes of approximately 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, and 0.5 mL. In some embodiments, the QIV-HD vaccine composition contains approximately 30 μg of HA per strain per dose in volumes of approximately 0.35 mL. In some embodiments, the QIV-HD vaccine composition contains approximately 30 μg of HA per strain per dose in volumes of approximately 0.35 mL, and the vaccine composition contains HA from Yamagata lineage influenza B virus strains, HA from Victoria lineage influenza B virus strains, HA from H1N1 influenza A virus strains, and HA from H3N2 influenza A virus strains. In some embodiments, the QIV-HD vaccine composition contains approximately 30 μg of HA per strain per dose in a pre-filled syringe in a volume of approximately 0.35 mL. In some embodiments, the QIV-HD vaccine composition contains approximately 30 μg of HA per strain per dose in a pre-filled syringe in a volume of approximately 0.35 mL, and the vaccine contains HA from Yamagata lineage influenza B virus strains, HA from Victoria lineage influenza B virus strains, HA from H1N1 influenza A virus strains, and HA from H3N2 influenza A virus strains.

[0099] In some embodiments, the QIV-HD vaccine composition contains approximately 45 μg of HA per strain per dose in a volume of approximately 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.52, 0.55, 0.6, 0.65, or 0.7 mL. In some embodiments, the QIV-HD vaccine composition contains approximately 45 μg of HA per strain per dose in a volume of approximately 0.5 mL or 0.52 mL. In some embodiments, the QIV-HD vaccine composition contains approximately 45 μg of HA per strain per dose in a volume of approximately 0.5 mL or 0.52 mL, and the vaccine composition contains HA from Yamagata lineage influenza B virus strains, HA from Victoria lineage influenza B virus strains, HA from H1N1 influenza A virus strains, and HA from H3N2 influenza A virus strains. In some embodiments, the QIV-HD vaccine composition contains approximately 45 μg of HA per strain per dose in a pre-filled syringe in a volume of approximately 0.5 mL or 0.52 mL. In some embodiments, the QIV-HD vaccine composition contains approximately 45 μg of HA per strain per dose in a pre-filled syringe in a volume of approximately 0.5 mL or 0.52 mL, and the vaccine composition includes HA from Yamagata lineage influenza B virus strains, HA from Victoria lineage influenza B virus strains, HA from H1N1 influenza A virus strains, and HA from H3N2 influenza A virus strains.

[0100] In some embodiments, the QIV-HD vaccine composition contains approximately 60 μg of HA per strain per dose in volumes of approximately 0.4, 0.45, 0.5, 0.55, 0.65, 0.7, 0.75, 0.8, 0.85, and 0.9 mL. In some embodiments, the QIV-HD vaccine composition contains approximately 60 μg of HA per strain per dose in volumes of approximately 0.7 mL. In some embodiments, the QIV-HD vaccine composition contains approximately 60 μg of HA per strain per dose in volumes of approximately 0.7 mL, and the vaccine composition includes HA from Yamagata lineage influenza B virus strains, HA from Victoria lineage influenza B virus strains, HA from H1N1 influenza A virus strains, and HA from H3N2 influenza A virus strains. In some embodiments, the QIV-HD vaccine composition contains approximately 60 μg of HA per strain per dose in volumes of approximately 0.7 mL in a pre-filled syringe. In some embodiments, the QIV-HD vaccine composition contains approximately 60 μg of HA per strain per dose in a pre-filled syringe in a volume of approximately 0.7 mL, and the vaccine composition includes HA from the Yamagata lineage influenza B virus strain, HA from the Victoria lineage influenza B virus strain, HA from the H1N1 influenza A virus strain, and HA from the H3N2 influenza A virus strain.

[0101] Typically, the concentration of HA is the same for each strain in the composition. However, in some embodiments, the concentration for each strain in the composition differs as long as the composition is a "high dose" (e.g., more than 15 μg of HA per dose).

[0102] Pharmaceutical composition In some embodiments, the QIV-HD vaccine comprises, in addition to the influenza antigen, components such as one or more pharmaceutically acceptable carriers, diluents, and / or excipients. In some embodiments, the vaccine composition comprises a pharmaceutically acceptable carrier, diluent, and / or excipient. In some embodiments, the vaccine composition comprises a pharmaceutically acceptable carrier, diluent, and / or excipient and an adjuvant. In some embodiments, the carrier, diluent, and / or excipient comprises buffered saline. In some embodiments, the carrier, diluent, and / or excipient comprises octylphenol ethoxylate (Triton X-100). In some embodiments, the carrier, diluent, and / or excipient comprises buffered saline and octylphenol ethoxylate (Triton X-100). In some embodiments, the carrier, diluent, and / or excipient comprises sodium chloride. In some embodiments, the carrier, diluent, and / or excipient comprises sodium phosphate. In some embodiments, the carrier, diluent, and / or excipient comprises disodium hydrogen phosphate. In some embodiments, the carrier, diluent, and / or excipient comprises water. In some embodiments, the carrier, diluent, and / or excipient comprises formaldehyde. In some embodiments, the carrier, diluent, and / or excipient comprises ovalbumin. In some embodiments, the carrier, diluent, and / or excipient comprises sodium chloride, sodium phosphate (mononucleotide, dinucleotide, or both), and water. In some embodiments, the carrier, diluent, and / or excipient comprises sodium chloride, sodium phosphate (mononucleotide, dinucleotide, or both), water, formaldehyde, ovalbumin, and Triton X-100.

[0103] The composition becomes aqueous when administered, but can be stored in solid form and resuspended before administration.

[0104] In some embodiments, the QIV-HD vaccine composition includes a preservative (e.g., thiomersal or 2-phenoxyethanol). However, in some embodiments, the vaccine composition is substantially free of mercury materials, and does not include, for example, thiomersal. In some embodiments, the vaccine composition does not contain a preservative.

[0105] In some embodiments, the vaccine composition contains a physiological salt, such as a sodium salt. In some embodiments, the vaccine composition contains sodium chloride (NaCl). In some embodiments, the vaccine composition contains NaCl between about 1 and 20 mg / ml. In some embodiments, the vaccine composition contains about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 g / L of NaCl. Other possible salts include sodium phosphate, potassium chloride, potassium dihydrogen phosphate, disodium phosphate, disodium phosphate anhydrous, magnesium chloride, magnesium chloride hexahydrate, calcium chloride dihydrate, or others known to those skilled in the art. In some embodiments, the vaccine composition contains about 0.1, 0.2, 0.2, 0.4, or 0.5 g / L of sodium dihydrogen phosphate. In some embodiments, the vaccine composition contains about 1, 2, 3, 4, or 5 g / L of disodium hydrogen phosphate. In some embodiments, the vaccine composition contains about 0.1, 0.2, 0.2, 0.4, or 0.5 g / L of sodium dihydrogen phosphate and about 1, 2, 3, 4, or 5 g / L of disodium hydrogen phosphate. If the adjuvant is in a separate container from the antigen, a salt, such as sodium chloride, may be present in both containers. In some embodiments, the vaccine composition contains about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 g / L of NaCl, about 0.1, 0.2, 0.2, 0.4, or 0.5 g / L of sodium dihydrogen phosphate and about 1, 2, 3, 4, or 5 g / L of disodium hydrogen phosphate. If the adjuvant is in a separate container from the antigen, a salt, such as sodium chloride, may be present in both containers.

[0106] In some embodiments, the QIV-HD vaccine composition comprises one or more buffers. Typical buffers include: phosphate buffer; Tris buffer; borate buffer; succinate buffer; histidine buffer (especially those with an aluminum hydroxide adjuvant); or citrate buffer. The buffers are typically contained in a concentration ranging from 5 to 20 mM. The pH of the composition is generally between 5.0 and 8.1, more typically between 6.0 and 8.0, for example, between 6.5 and 7.5, or between 7.0 and 7.8.

[0107] In some embodiments, the vaccine composition is sterile. The composition is preferably non-pyrogenic and contains, for example, less than 1 EU (endotoxin units, standard measurement) per dose, preferably <0.1 EU per dose. The composition is preferably gluten-free.

[0108] The compositions of the present invention, particularly for split or surface antigen vaccines, may include surfactants, such as polyoxyethylene sorbitan ester surfactants (known as "Tweens"), octoxynols (e.g., octoxynol-9 (Triton X-100) or t-octylphenoxypolyethoxyethanol), cetyltrimethylammonium bromide ("CTAB"), or sodium deoxycholate. The surfactant may be present only in trace amounts. In some embodiments, the vaccine composition for use in the methods disclosed herein includes trace amounts of other remaining components, such as antibiotics (e.g., neomycin, kanamycin, or polymyxin B). If the adjuvant is in a separate container from the antigen, the surfactant is typically present in the container containing the antigen.

[0109] In some embodiments, the vaccine composition comprises a unit dose volume of approximately 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, or 0.7 mL, and a pharmaceutically acceptable carrier(s), diluent(s), and / or excipient(s).

[0110] Adjuvant In some embodiments, the QIV-HD vaccine composition includes one or more adjuvants that can function to enhance the (humoral and / or cellular) immune response induced in a patient administered the composition. In some embodiments, the vaccine composition includes an oil-in-water emulsion adjuvant. In some embodiments, the vaccine composition includes squalene.

[0111] In some embodiments, the vaccine composition comprises an oil-in-water emulsion and at least one surfactant.

[0112] In some embodiments, the vaccine composition includes tocopherol.

[0113] In some embodiments, the vaccine composition includes tocopherol and squalene. In one embodiment, the oil content is in the range of 2-20% (by volume).

[0114] In some embodiments, the vaccine composition includes an adjuvant comprising a mineral-containing composition comprising calcium salts and aluminum salts (or mixtures thereof). Examples of calcium salts include calcium phosphate. Aluminum salts include hydroxides, phosphates, sulfates, etc., and the salts take any preferred form (e.g., gel, crystal, amorphous, etc.). The mineral-containing composition can also be formulated as particles of the metal salt.

[0115] In some embodiments, the vaccine composition includes an adjuvant comprising one or more saponins, which are a heterogeneous group of sterol glycosides and triterpenoid glycosides found in the bark, leaves, stems, roots, and even flowers of a wide range of plant species. Saponins from Quillaja bark have been widely studied as adjuvants. Saponins can also be commercially available from Smilax ornata (Sarsaparilla), Perennial Gypsophila (Brides Veil), and Soapwort.

[0116] Saponin adjuvant formulations include purified formulations, such as QS21, and lipid formulations, such as ISCOM. QS21 is marketed as Stimulon®. Combinations of saponins and cholesterol can be used to form unique particles called immunostimulatory complexes (ISCOMs). In some embodiments, ISCOMs include phospholipids, such as phosphatidylethanolamine or phosphatidylcholine. Any known saponin can be used in ISCOMs. Preferably, ISCOMs contain one or more of:QuilA, QHA, and QHC.

[0117] In some embodiments, the vaccine composition includes an adjuvant containing a lipid adjuvant.

[0118] In some embodiments, the vaccine composition includes an adjuvant comprising a bacterial ADP-ribosylated toxin (e.g., Escherichia coli thermolabile enterotoxin "LT", cholera toxin "CT", or pertussis toxin "PT") and its detoxification derivatives, such as mutagens known as LT-K63 and LT-R72.

[0119] In some embodiments, the vaccine composition includes an adjuvant comprising a bioadhesive and a mucosal adhesive, such as ester-type hyaluronic acid microspheres or chitosan and its derivatives.

[0120] In some embodiments, the vaccine composition includes an adjuvant containing a cytokine inducer.

[0121] In some embodiments, the vaccine composition includes an adjuvant containing liposomes.

[0122] In some embodiments, the vaccine composition includes an adjuvant comprising a polyoxyethylene ether and / or a polyoxyethylene ester. Such formulations include polyoxyethylene sorbitan ester surfactants combined with octoxynol, and further include at least one additional nonionic surfactant, such as a polyoxyethylene alkyl ether or ester surfactant combined with octoxynol. Representative polyoxyethylene ethers are selected from the following group: polyoxyethylene-9-lauryl ether (laureth-9), polyoxyethylene-9-steoryl ether, polyoxyethylene-8-steoryl ether, polyoxyethylene-4-lauryl ether, polyoxyethylene-35-lauryl ether, and polyoxyethylene-23-lauryl ether.

[0123] In some embodiments, the vaccine composition includes an adjuvant comprising a muramyl peptide, such as N-acetylmuramyl-L-treoil-D-isoglutamine ("thr-MDP"), N-acetyl-normuramyl-L-alanyl-D-isoglutamine (nor-MDP), N-acetylglucasaminyl-N-acetylmuramyl-L-Al-D-isoglu-L-Ala-dipalmitoxypropylamide ("DTP-DPP", or Theramide®), or N-acetylmuramyl-L-alanyl-D-isoglutaminyl-L-alanine-2-(1'-2'dipalmitoyl-sn-glycero-3-hydroxyphosphoryloxy)-ethylamine ("MTP-PE").

[0124] The composition may contain one or more adjuvants, for example, two, three, four or more adjuvants. For example, these may advantageously include both oil-in-water emulsions and cytokine inducers.

[0125] The antigen and adjuvant in the composition are typically present in a mixture.

[0126] vaccine production In some embodiments, the QIV-HD vaccine composition is produced in eggs. In some embodiments, the eggs are chicken eggs, for example, hen eggs. In some embodiments, the vaccine composition is produced in cell lines that assist in the replication of the influenza virus. The cell lines are typically of mammalian origin. Suitable mammalian cells include those of hamsters, cattle, primates (including humans and monkeys), and dogs. Various cell types can be used, such as kidney cells, fibroblasts, retinal cells, lung cells, etc. An example of a suitable hamster cell is a cell line named BHK21 or HKCC. Suitable monkey cells are, for example, African green monkey cells, such as kidney cells like the Vero cell line. Suitable dog cells are, for example, kidney cells like the CLDK and MDCK cell lines.

[0127] In some embodiments, the vaccine composition is produced using cell lines having mammalian glycosylation. In some embodiments, the vaccine composition is produced using avian cell lines, including cell lines derived from ducks and hens.

[0128] In some embodiments, the vaccine composition is prepared using an MDCK cell line derived from Maidin-Derby canine kidney. The original MDCK cell line is available from ATCC as CCL-34, but derivatives of this cell line and other MDCK cell lines can also be used.

[0129] In some embodiments, the vaccine composition is grown in adherent culture or in a suspension. Microcarrier culture can also be used. In some embodiments, cells may be suitable for growth in a suspension in this manner.

[0130] In some embodiments, the vaccine composition is prepared in a cell line, and optionally the cells are grown in serum-free culture media and / or protein-free media. If no additives from human or animal serum are present, the medium is referred to as serum-free medium in the context of this disclosure. Cells grown in such cultures naturally contain proteins themselves, but protein-free medium is understood to mean one in which cell proliferation (e.g., pre-infection) occurs without proteins, growth factors, other protein additives and serum-free proteins, but which optionally may contain proteins that may be necessary for viral growth, such as trypsin or other proteases.

[0131] In some embodiments, the vaccine composition is produced in cell lines, which assist in influenza virus replication and grow at temperatures below 37°C (e.g., 30-36°C or approximately 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C) during viral replication.

[0132] A method for growing influenza virus in cultured cells generally includes the steps of: inoculating a cell culture with a starter culture of the strain to be grown; collecting the infected cells at a desired period for viral growth (e.g., between 24 and 168 hours after inoculation), which is determined, for example, by viral titer or antigen expression; and collecting the grown virus.

[0133] The virus inoculum and virus cultures are preferably free from herpes simplex virus, respiratory syncytial virus (RSV), parainfluenza virus type 3, SARS coronavirus, adenovirus, rhinovirus, reovirus, polyomavirus, bimaviruses, circovirus, and / or parvovirus (i.e., tested and negative for contamination by these).

[0134] Typical methods and uses A method for immunizing a pediatric subject against the influenza virus is provided, comprising the step of administering a QIV-HD vaccine to the pediatric subject. In some embodiments, the QIV-HD vaccine is provided for use in immunizing a pediatric subject. A QIV-HD vaccine composition is provided for use in the preparation of a pharmaceutical for immunizing a pediatric subject against influenza. In some embodiments, the pediatric subject is between 6 months and under 18 years of age.

[0135] A method and use for immunizing a pediatric subject against influenza virus is provided, comprising the step of administering to the pediatric subject a QIV-HD vaccine containing: approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from an H1N1 influenza A virus strain; approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from an H3N2 influenza A virus strain; approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from a Yamagata lineage influenza B virus strain; and approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from a Victoria lineage influenza B virus strain; the method and use are provided for a pediatric subject being between 6 months and under 18 years of age. The subject may be a human.

[0136] The disclosed methods and uses are generally, but not limited to, those used to generate antibody responses, including protective antibody responses. Methods for evaluating antibody responses, neutralizing ability, and protection after influenza virus vaccination are well known in the art. Human studies have shown that antibody titers against hemagglutinin of human influenza virus correlate with protection (a hemagglutinin inhibitory titer of approximately 30-40 in serum samples results in approximately 50% protection from homologous virus infection). Antibody responses are typically measured by hemagglutination inhibition (HAI), microneutralization tests, one-way radial immunodiffusion (SRID), and / or one-way radial diffusion hemolysis (SRH). These assay techniques are well known in the art.

[0137] Hemagglutination inhibition (HAI) assays are a common method for determining quantitative antibody titers against influenza virus and are widely used both for vaccine licensing and for seroepidemiological studies to examine protection in populations. The assay relies on the ability of the hemagglutinin protein on the surface of the influenza virus to bind to sialic acid on the surface of red blood cells (RBCs). This interaction is inhibited if the patient's serum contains antibodies that prevent viral attachment.

[0138] In some embodiments, a method is provided for immunizing a pediatric subject against influenza virus, comprising the step of administering a QIV-HD vaccine composition to the pediatric subject. In some embodiments, the QIV-HD vaccine composition comprises: i) approximately 30 μg, approximately 45 μg, or approximately 60 μg of hemagglutinin from an H1N1 influenza A virus strain per dose; ii) approximately 30 μg, approximately 45 μg, or approximately 60 μg of hemagglutinin from an H3N2 influenza A virus strain per dose; iii) approximately 30 μg, approximately 45 μg, or approximately 60 μg of hemagglutinin from a Yamagata lineage influenza B virus strain per dose; and iv) approximately 30 μg, approximately 45 μg, or approximately 60 μg of hemagglutinin from a Victoria lineage influenza B virus strain per dose. In some embodiments, the pediatric subject is between 6 months and under 18 years of age.

[0139] In some embodiments, a method is provided for inducing a protective immune response against influenza virus in a pediatric subject, comprising the steps of administering to the pediatric subject a QIV-HD vaccine composition comprising: i) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from an H1N1 influenza A virus strain; ii) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from an H3N2 influenza A virus strain; iii) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from a Yamagata lineage influenza B virus strain; and iv) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from a Victoria lineage influenza B virus strain; and the method is provided for a pediatric subject between 6 months and under 18 years of age.

[0140] In some embodiments, a method for preventing influenza in a child is provided, comprising the step of administering to a child a QIV-HD vaccine composition comprising: i) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from an H1N1 influenza A virus strain; ii) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from an H3N2 influenza A virus strain; iii) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from a Yamagata lineage influenza B virus strain; and iv) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from a Victoria lineage influenza B virus strain; and a method is provided for a child between 6 months and under 18 years of age.

[0141] In some embodiments, a method is provided for generating antibodies against influenza viruses in a pediatric subject, comprising the steps of administering to the pediatric subject a QIV-HD vaccine composition comprising: i) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from an H1N1 influenza A virus strain; ii) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from an H3N2 influenza A virus strain; iii) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from a Yamagata lineage influenza B virus strain; and iv) approximately 30 μg, approximately 45 μg, or approximately 60 μg per dose of hemagglutinin from a Victoria lineage influenza B virus strain; and the method is provided for a pediatric subject between 6 months and under 18 years of age.

[0142] In some embodiments, a method is provided for immunizing a pediatric subject against an influenza virus, comprising the steps of administering to the pediatric subject a high dose of an influenza vaccine composition comprising: i) approximately 30 μg per dose of hemagglutinin from an H1N1 influenza A virus strain; ii) approximately 30 μg per dose of hemagglutinin from an H3N2 influenza A virus strain; iii) approximately 30 μg per dose of hemagglutinin from a Yamagata lineage influenza B virus strain; and iv) approximately 30 μg per dose of hemagglutinin from a Victoria lineage influenza B virus strain; the method is provided for a pediatric subject between 6 months and under 18 years of age.

[0143] In some embodiments, a method is provided for immunizing a pediatric subject against an influenza virus, comprising the steps of administering to the pediatric subject a high dose of an influenza vaccine composition comprising: i) approximately 45 μg per dose of hemagglutinin from an H1N1 influenza A virus strain; ii) approximately 45 μg per dose of hemagglutinin from an H3N2 influenza A virus strain; iii) approximately 45 μg per dose of hemagglutinin from a Yamagata lineage influenza B virus strain; and iv) approximately 45 μg per dose of hemagglutinin from a Victoria lineage influenza B virus strain; the method is provided for a pediatric subject between 6 months and under 18 years of age.

[0144] In some embodiments, a method is provided for immunizing a pediatric subject against an influenza virus, comprising the steps of administering to the pediatric subject a high dose of an influenza vaccine composition comprising: i) approximately 60 μg per dose of hemagglutinin from an H1N1 influenza A virus strain; ii) approximately 60 μg per dose of hemagglutinin from an H3N2 influenza A virus strain; iii) approximately 60 μg per dose of hemagglutinin from a Yamagata lineage influenza B virus strain; and iv) approximately 60 μg per dose of hemagglutinin from a Victoria lineage influenza B virus strain; the method is provided for a pediatric subject between 6 months and under 18 years of age.

[0145] In some embodiments, the target age group is 6 months to under 18 years. In some embodiments, the target age group is 9 to 17 years. In some embodiments, the target age group is 5 to 8 years. In some embodiments, the target age group is 36 months to under 5 years. In some embodiments, the target age group is 6 months to under 36 months. In some embodiments, the target age group is 6 months to under 24 months. In some embodiments, the target age group is 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, or 36 months. In some embodiments, the target age group is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17 years. In some embodiments, the child subjects have not been previously vaccinated. In some embodiments, the child subjects have been previously vaccinated. In some embodiments, the child subjects have had a prior influenza infection. In some embodiments, the child subjects have not had a prior influenza infection.

[0146] In some embodiments, the target children are between 6 months and under 18 years old and have either been previously vaccinated or not. In some embodiments, the target children are between 9 and 17 years old and have either been previously vaccinated or not. In some embodiments, the target children are between 5 and 8 years old and have either been previously vaccinated or not. In some embodiments, the target children are between 36 months and under 5 years old and have either been previously vaccinated or not. In some embodiments, the target children are between 6 months and under 36 months old and have either been previously vaccinated or not. In some embodiments, the target children are between 6 months and under 24 months old and have either been previously vaccinated or not.

[0147] In some embodiments, the pediatric subjects are approximately 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 months of age. In some embodiments, the pediatric subjects are approximately 6, 7, 8, 9, 10, 11, or 12 months of age. In some embodiments, the pediatric subjects are approximately 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24 months of age. In some embodiments, the pediatric subjects are approximately 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17 years of age. In some embodiments, the pediatric subjects are between 6 months and 9 years of age. In some embodiments, the pediatric subjects are between 6 months and 9 years of age and are provided with two doses of the QIV-HD vaccine. In some embodiments, the pediatric subjects are between 6 months and 9 years of age and are provided with two doses of the QIV-HD vaccine at least 4 weeks apart. In some embodiments, the child subject is between 6 months and 9 years of age, has not previously been vaccinated against the influenza virus, and is provided with two doses of the QIV-HD vaccine. In some embodiments, the child subject is between 6 months and 9 years of age, has previously been vaccinated against the influenza virus, and is provided with one dose of the QIV-HD vaccine.

[0148] In a typical embodiment, children aged 6 months to under 9 years who have not previously received an influenza vaccine are given two doses of the QIV-HD vaccine at least 28 days apart during the influenza season.

[0149] In a typical embodiment, children aged 6 months to under 9 years who have previously received an influenza vaccine are given one dose of the QIV-HD vaccine.

[0150] In a typical embodiment, children aged 9 to under 18 years are given one dose of QIV-HD vaccine, regardless of their previous influenza vaccination history.

[0151] In some embodiments, previously unvaccinated children are those who have not received at least two doses of seasonal influenza vaccine during the previous influenza season, or who have received only one dose of any influenza vaccine in the past, or whose vaccination history is unknown. In some embodiments, previously vaccinated children are those who have received at least two doses of seasonal influenza vaccine during the previous influenza season.

[0152] In some embodiments, the QIV-HD vaccine is provided for use in a method for preventing influenza virus infection in a pediatric subject, which is a method for immunizing against influenza, inducing a protective immune response, or producing antibodies against it. In some embodiments, the QIV-HD vaccine comprises one of the compositions described herein in one of the doses described herein. In some embodiments, the QIV-HD vaccine is administered in doses of approximately 30 μg, approximately 45 μg, or approximately 60 μg of hemagglutinin per strain and has one or more functional effects of preventing influenza, inducing a protective immune response against influenza, or producing an antibody response against influenza.

[0153] In some embodiments, the method or use elicits a protective immune response in pediatric subjects. In some embodiments, the immune response is an antibody response.

[0154] The QIV-HD vaccine can be administered to selected pediatric subjects using any of a number of conventional methodologies, including, for example, parenteral, intravenous, intraperitoneal, subcutaneous, transcutaneous, intradermal, subdermal, transdermal, intramuscular, topical, intranasal, or other preferred routes of administration, such as injection, inhalation, gas infusion, or ingestion. In some embodiments, the vaccine is administered intramuscularly.

[0155] Administration can be via a single-dose schedule or a multi-dose schedule. Multi-dose schedules can be used in primary and / or booster immunization schedules. In multi-dose schedules, various doses may be administered via the same or different routes, for example, parenteral initial antigen stimulation and mucosal booster immunization, or mucosal initial antigen stimulation and parenteral booster immunization. Administration of more than one dose (typically two doses) is particularly useful in subjects that have not been previously vaccinated, such as immunologically naive patients, for example, people who have never received an influenza vaccine before, or people who have never been infected with influenza, or for vaccines containing a new HA subtype. Multi-dose schedules are typically administered at least one week apart (e.g., about two weeks, three weeks, four weeks, six weeks, eight weeks, twelve weeks, sixteen weeks, etc.). In some embodiments, the vaccine is administered once or twice to a single subject. In some embodiments, the vaccine is administered in a single dose. In some embodiments, the two doses are provided with an interval of approximately 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 days between doses. In some embodiments, the two doses are provided with an interval of approximately 28 days between doses.

[0156] In some embodiments, the two-dose vaccine is administered to subjects who have not been vaccinated against influenza, and the administration of the two-dose vaccine results in a higher geometric mean titer (GMT) for each of the strains used for vaccination compared to vaccination using QIV-SD. In some embodiments, the two-dose vaccine is administered to subjects who have not been vaccinated against influenza, and the administration of the two-dose vaccine results in a higher geometric mean titer (GMT) for each of the strains used for vaccination compared to vaccination using QIV-SD. In some embodiments, the two-dose vaccine is administered to children aged approximately 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 months. In some embodiments, the children are aged approximately 6, 7, 8, 9, 10, 11, or 12 months. In some embodiments, the children are aged approximately 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17 years. In some embodiments, the vaccine is administered in a pre-filled syringe. In some embodiments, the pre-filled syringe contains only the volume necessary to include the QIV-HD vaccine, and the volume generally increases with increasing dose.

[0157] In some embodiments, the administration reduces the incidence of laboratory-confirmed influenza-like illness. In some embodiments, the administration reduces the incidence of laboratory-confirmed influenza-like illness compared to vaccination of similar age subjects with a standard dose of vaccine (e.g., TIV-SD or QIV-SD). In some embodiments, laboratory-confirmed influenza-like illness is defined as the occurrence of a fever of 38°C or above or equal to 38°C for at least 24 hours. In some embodiments, laboratory-confirmed influenza-like illness is defined as at least one of the following: cough, sputum production, wheezing, dyspnea, nasal congestion, rhinorrhea, pharyngitis, otitis media, vomiting, diarrhea, sore throat, chills (shivering), fatigue (malaise), headache, and muscle aches (muscle pain). In some embodiments, a test-confirmed influenza-like illness is defined as the occurrence of a fever of 38°C or above or equal to 38°C for at least 24 hours, as well as at least one of the following: cough, sputum production, wheezing, dyspnea, nasal congestion, rhinorrhea, pharyngitis, otitis media, vomiting, diarrhea, sore throat, chills (shivering), fatigue (malaise), headache, and muscle pain (muscle pain). In some embodiments, administration of QIV-HD reduces the occurrence of a test-confirmed influenza-like illness caused by a virus type / subtype antigenically similar to that contained in the vaccine composition.

[0158] In some embodiments, administration reduces the occurrence of at least one of the following: acute otitis media (AOM), acute lower respiratory tract infection (ALRI, e.g., pneumonia), hospitalization, and / or drug use.

[0159] In some embodiments, administration of the QIV-HD vaccine results in higher geometric mean titers (GMT) for each of the strains used for vaccination compared to vaccination with QIV-SD, TIV-SD, and / or TIV-HD.

[0160] In some embodiments, administration of the QIV-HD vaccine results in higher serum neutralization against each of the strains used for vaccination compared to vaccination with QIV-SD, TIV-SD, and / or TIV-HD. In some embodiments, administration of the QIV-HD vaccine results in higher serum neutralization against each of the strains used for vaccination compared to vaccination with QIV-SD, TIV-SD, and / or TIV-HD, and the subjects are between 6 months and under 3 years of age. In some embodiments, the pediatric subjects are approximately 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 months of age. In some embodiments, the pediatric subjects are approximately 6, 7, 8, 9, 10, 11, or 12 months of age. In some embodiments, the pediatric subjects are approximately 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17 years of age.

[0161] In some embodiments, administration of the QIV-HD vaccine to children results in a geometric mean HI antibody titer (GMT) ratio (QIV-HD / QIV-SD) that is higher than the TIV-HD / TIV-SD GMT ratio in adults aged 65 years or older who have received QIV-SD, TIV-SD, or TIV-HD. In some embodiments, administration of the QIV-HD vaccine to subjects between 6 months and under 3 years of age results in a geometric mean HI antibody titer (GMT) ratio (QIV-HD / QIV-SD) that is higher than the TIV-HD / TIV-SD GMT ratio in adults aged 65 years or older who have received QIV-SD, TIV-SD, or TIV-HD.

[0162] In some embodiments, the pediatric subjects are immunocompromised. In some embodiments, the pediatric subjects are at high risk. In some embodiments, subjects are considered at high risk if they have one or more of the following conditions: asthma, neurological and / or neurodevelopmental conditions (disorders of the brain, spinal cord, peripheral nerves and muscles, e.g., cerebral palsy, epilepsy (paroxysmal disorder), stroke, intellectual disability (mental retardation), moderate to severe developmental delay, muscular dystrophy or spinal cord injury), chronic lung disease (e.g., cystic fibrosis), heart disease (e.g., congenital heart disease, congestive heart failure and coronary artery disease), blood disorders (e.g., sickle cell anemia), endocrine disorders (e.g., diabetes mellitus), renal disorders, hepatic disorders, metabolic disorders (e.g., hereditary metabolic disorders and mitochondrial disorders), weakened immune system due to disease or drug (e.g., HIV or AIDS, children or adolescents with cancer, or children or adolescents using chronic steroids), or children taking drugs containing aspirin or salicylates. Extreme obesity, which has been associated with severe influenza illness in some adult studies, may also be a risk factor in children. Childhood obesity is defined as a body mass index (BMI) that is at or above the 95th percentile for age and sex.

[0163] In some embodiments, high-risk individuals are immunocompromised or have one or more of the following conditions: diabetes (type 1 or type 2), heart disease, asthma, lung condition, liver disease, renal / kidney disease, HIV, AIDS, or cancer.

[0164] In some embodiments, the vaccine compositions described herein are administered concurrently with other routine vaccines. In some embodiments, the routine vaccines include, for example, Pentacel® (DTaP5-IPV / Hib), Prevnar® (PCV7), Prevnar 13® (PCV13), RotaTeq® (RV5), ROTARIX® (RV1), ENGERIX-B® (HepB), RECOMBIVAX HB® (HepB), MMR® (MMR), and MMR®.II Examples include (MMR) and VARIVAX®(V) vaccines. In some embodiments, routine vaccines include, for example, Adacel®(Tdap5) and Gardasil®(HPV4). In some embodiments, routine vaccines include DTaP5-IPV / HibHepB, and other routine vaccines are known in the art and can be provided to the target simultaneously with, before, or after the vaccine compositions described herein. ***

[0165] This description and representative embodiments should not be considered limiting. For the purposes of this specification and the attached claims, unless otherwise specified, all numbers representing quantities, percentages or proportions, and other numerical values ​​used herein and in the claims, should be understood in all cases to be modified by the term “about,” to the extent they have not yet been modified in that way. “About” represents a degree of variation that does not substantially affect the properties of the subject matter described, for example, within 10%, 5%, 2%, or 1%. Thus, unless otherwise indicated, the numerical parameters described herein and in the attached claims are approximations that may vary depending on the desired properties to be obtained. At a minimum, and not in an attempt to limit the application of the theory of equivalents to the claims, each numerical parameter should be interpreted at least in light of the reported significant figures and by applying the usual techniques of rounding.

[0166] When used herein and in the appended claims, the singular forms “a,” “an,” and “the,” and any singular use of any term, should be noted as including multiple referents unless explicitly and explicitly limited to a single referent. When used herein, the term “including” and its grammatical variations are intended to be non-restrictive so as not to exclude other similar items that could substitute for or be added to the listed items. [Examples]

[0167] The following embodiments are provided to illustrate certain specific embodiments of the disclosure and should not be construed as limiting the scope of the disclosure. [Examples]

[0168] Safety and immunogenicity of high-dose quadrivalent influenza vaccine (QIV-HD) at different dosages in children aged 6 months to under 18 years. A randomized, dose-escalating, modified double-blind, active-controlled, multicenter Phase II trial was conducted in children aged 6 months to <18 years. The primary objectives were to evaluate the safety of QIV-HD administered in one or two doses at three dose levels (30, 45, and 60 μg HA / strain) in the study age group; to compare the antibody response induced by QIV-HD versus QIV-SD at each study dose; and to compare the antibody response induced by QIV-HD versus adjuvanted TIV at the maximum tolerated dose.

[0169] Participants were enrolled in four stages using a stepwise age-decreasing and dose-escalating design. In the US cohort, participants were randomized to receive one of two dose levels of QIV-HD or QIV-SD. In the Canadian cohort, participants were randomized to receive the maximum tolerated QIV-HD dose along with adjuvanted TIV. For participants 8 years of age or younger, a blinded review of 7-day safety data for each trial QIV-HD dose was performed to determine whether to proceed to the next planned dose.

[0170] All subjects enrolled in the QHD04 trial (also known as the QHD4 trial) received either one of three clinical trials, QIV-HD, which differed in the amount of HA per strain, or one of two approved comparative vaccines, QIV-SD or adjuvanted TIV (Fluad®). Subjects were vaccinated against influenza viruses recommended by the WHO (Vaccines and Related Biological Products Advisory Committee [VRBPAC] in the United States) for the 2018-2019 Northern Hemisphere (NH) influenza season.

[0171] The study designs, vaccine content, and baseline characteristics for the US and Canadian cohorts are shown in Tables 1A, 1B, 1C, and 1D, respectively.

[0172] Examination Procedures: Participants: Participants had to be between 6 months and <18 years of age. Participants <24 months of age had to be born at full term (≥37 weeks) or have a birth weight of ≥2.5 kg. Participants who had received any vaccine in the 30 days prior to the study vaccine were excluded. Participants who had previously received the influenza vaccine had not received any further influenza vaccines in the preceding 6 months. Unvaccinated participants had not received the influenza vaccine or had a confirmed influenza infection by testing. Participants were excluded if, in the opinion of the principal investigator, there were conditions that could compromise the participant's health or the evaluation of the study vaccine. Other exclusion criteria are listed in Table 5A.

[0173] Vaccine and administration: QIV-HD is a split-virion inactivated influenza vaccine containing 30, 45, or 60 μg HA / strain of A / H1N1, A / H3N2, B / Victoria, and B / Yamagata virus strains recommended by the World Health Organization (WHO) / US Vaccines and Related Biological Products Advisory Committee for the 2018-2019 Northern Hemisphere influenza season. QIV-SD (Fluarix Quadrivalent; GlaxoSmithKline Biologicals, Dresden, Germany) is a split-virion inactivated influenza vaccine containing 15 μg HA / strain of A / H1N1, A / H3N2, B / Victoria, and B / Yamagata virus strains recommended by the WHO / US Vaccines and Related Biological Products Advisory Committee for the 2018-2019 Northern Hemisphere influenza season. MF59-adjuvanted TIV (FLUAD Pediatric; Seqirus UK Limited, Madeonhead, UK) contains 7.5 μg per strain of A / H1N1, A / H3N2, and B / Victoria virus strains as recommended by the WHO / National Advisory Committee on Immunization of Canada for the Northern Hemisphere 2018-2019 influenza season.

[0174] Participants aged 9 to <18 years, and participants aged 6 months to <9 years who had previously received an influenza vaccine, received one dose of either QIV-HD or the comparative vaccine. Participants aged 6 months to <9 years who had never received an influenza vaccine or who had received only one dose in the previous influenza season, received two doses of either QIV-HD or the comparative vaccine at 28-day intervals. All vaccines were administered by intramuscular injection. Table 20A shows the vaccines received by the study group and the vaccinated group. Table 1B summarizes the antigen content and injection volume of each study QIV-HD dose.

[0175] Randomization: The trial was divided into 13 trial groups. For each group, randomization was stratified by prior influenza vaccination status (previously vaccinated or unvaccinated). Using two-way response technology, eligible participants were randomized according to the randomization schedule shown in Table 16A.

[0176] Blinding: The trial was a modified double-blind study: open-label staff at each facility administered the vaccine, and their identity was not disclosed to the principal investigator responsible for safety evaluation, the trial staff who collected safety data, the laboratory staff who analyzed blood samples, the participants, or the participants' parents or guardians. Those who administered the vaccine were not involved in any blinded trial evaluation.

[0177] Measurement of hemagglutination inhibitor (HAI) antibody titers: Participants provided blood samples on the day of the first vaccine administration (baseline) and 28–35 days after each vaccine administration. HAI titers were measured as previously described (Greenberg DP et al. (2013) Vaccines 31:770-6). Briefly, serum samples were isolated from collected blood and incubated with control serum with Vibrio cholerae type 3 neuraminidase to remove nonspecific inhibitors. These were then incubated with erythrocyte suspension to adsorb spontaneous anti-agglutinins. The mixtures were then centrifuged, and the resulting supernatant was used to prepare 10 2-fold dilutions (range 1:10 to 1:10,240), which were incubated with pre-titrated influenza antigen (4 hemagglutination units / 25 mL). Erythrocyte suspensions were added to the mixtures and incubated. Titers were then recorded as the highest serum dilution at which complete HAI occurred. If complete inhibition of hemagglutination was not achieved with a 1:10 dilution, the HAI titer was reported as <10. If complete inhibition of hemagglutination was achieved with a 1:10,240 dilution, the serum HAI titer was reported as ≥10,240. Endpoints based on HAI antibody titers included titer at 28 days post-vaccination, the ratio of post-vaccination to pre-vaccination titer, and the seroconversion rate (defined as the percentage of participants who had a titer <10 before vaccination and a titer ≥40 after vaccination, or (ii) a titer ≥10 before vaccination and an ≥4-fold increase in titer after vaccination).

[0178] Measurement of serum neutralizing antibody titers: Neutralizing activity was analyzed using a microneutralizing assay based on the methods of the Centers for Disease Control and Prevention and the U.S. Agency for Health Protection's influenza standard laboratory (Stephenson I et al. (2004) Virsus Res 103:;91-5; Rowe T et al. (1999) J Clin Microbiol 37:937~43). Serially diluted, heat-inactivated human serum samples were pre-incubated with a fixed amount of challenge virus. These were then incubated overnight with Madin-Darby canine kidney cells, and viral nucleoprotein production in infected cells was subsequently measured by an enzyme-linked immunosorbent assay using monoclonal antibodies specific to influenza A or influenza B nucleoprotein. Neutralizing antibody titers were defined as the reciprocal of the highest dilution that yielded optical density equivalent to a 50% reduction in the detection of influenza virus NPs. The limit of quantification was the reciprocal of the lowest dilution used (1:10). Titers smaller than this were reported as <10. Samples with a potency > 10240 were pre-diluted, retested, and the endpoint potency was reported.

[0179] Responses from involuntary reporting: On the day of each vaccine administration and for 7 days after vaccination, each participant (or their parent or guardian) recorded daily body temperature (and the route of measurement) and other involuntary reports of injection site and systemic reactions (including severity grade) using a diary card. For each event, any actions taken by the participant or their parent or guardian (e.g., discontinuation of the study vaccine) were to be recorded. Injection site reactions included pain (in children aged 3 to <18 years) or tenderness (in children aged 6 months to <3 years), erythema, swelling, induration, and bruising. Systemic reactions in children aged 3 to <18 years included fever, headache, malaise, muscle pain, and shivering. In children aged 6 months to <3 years, systemic reactions included fever, vomiting, excessive crying, somnolence, loss of appetite, and irritability. Involuntary reports of reactions were graded as follows: severe was graded 3, moderate 2, and mild 1 (see Table 16B for grading of involuntary injection site reactions and Table 16C for grading of involuntary systemic reactions).

[0180] Adverse events reported voluntarily: Spontaneous reported AEs and SAEs were defined as described in the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use E2A Guidelines for Clinical Safety Data Management: Definition and Criteria for Emergency Reporting (ICH.E2A.:(1995) Clinical Safety Data Management: Definition and Criteria for Emergency Reporting. Japan-US-EU International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use), and were collected for 28 days after each vaccine administration. Spontaneous reported systemic AEs occurring within the first 30 minutes after vaccination were recorded as immediate spontaneously reported systemic AEs.

[0181] SAEs (including particularly noteworthy AEs) were collected up to 6 months after the last dose of the vaccine. Particularly noteworthy AEs included new-onset Guillain-Barré syndrome, encephalitis / myelitis (including transverse myelitis), Bell's palsy, seizures (including febrile seizures), optic neuritis, and brachial neuritis. All AEs were evaluated for intensity, severity, association with the study vaccine, and the actions taken.

[0182] Statistical analysis: Immunogenic endpoints for HAI antibody titers (potency, post-vaccination titer-to-pre-vaccination titer ratio, and antibody seroconversion rate) and serum neutralizing antibody titers were analyzed in an immunogenicity analysis set defined as a randomized subset of participants who received either one dose of the study vaccine (9 to <18 years of age and previously vaccinated participants 6 months to <9 years of age) or two doses of the same study vaccine (6 months to <9 years of age of previously unvaccinated participants) and provided post-vaccination blood samples.

[0183] Geometric mean titers (GMT), the geometric mean of individual titer ratios (post-vaccination / pre-vaccination), and the ratio of GMTs between vaccine groups were calculated, and their 95% confidence intervals (CIs) were calculated using a normal approximation of logarithmically transformed titers. Antibody seroconversion rates were calculated, and 95% CIs were calculated using the Clopper-Pearson method (Newcombe RG (1998) Stat Med 17:857~72).

[0184] Involuntary reported responses and adverse events (AEs) were analyzed according to the vaccine received in the safety analysis set, which was defined as all participants who received at least one dose of the study vaccine. Descriptive statistics were calculated.

[0185] Missing data were not attributed, and no outlier search was performed. Since no hypotheses were tested, no statistical adjustments were made based on the results of the blinded safety review. Statistical analysis was performed using SAS version 9.4 or later (SAS Institute, Cary, NC, USA).

[0186] Sample size estimation: The study aimed to enroll approximately 700 participants and divide them into 13 groups, with the goal of having enough participants to observe trends in safety and immunogenicity (see Table 16A); however, since the hypothesis was not tested, the study size was not calculated.

[0187] [Table 2-1] [Table 2-2]

[0188] [Table 3]

[0189] [Table 4]

[0190] [Table 5]

[0191] [Table 6-1] [Table 6-2]

[0192] [Table 7]

[0193] [Table 8-1] [Table 8-2]

[0194] [Table 9-1] [Table 9-2]

[0195] detail: 1.1 - Theoretical basis of the test While influenza can affect all age groups, infants and young children remain at increased risk due to their maturing immune systems and lack of prior exposure, thus resulting in a lack of immunity. Therefore, following similar rationale to that applied to adults aged 65 and older, children may benefit from increased antigen doses. Thus, the Phase II trial evaluated whether increased antigen doses in the QIV-HD investigational drug were safe and improved immune responses in a pediatric population aged 6 months to under 18 years, compared to the currently approved standard-dose quadrivalent influenza vaccine (QIV-SD) (15 μg HA / strain). The goal of QHD04 was to select an appropriate vaccine dose to advance to Phase III clinical development.

[0196] QHD04 was conducted in approximately 661 children aged 6 months to under 18 years during the 2018-2019 NH influenza season, evaluating three different doses of QIV-HD in this pediatric population. The control vaccine was Fluarix Quadrivalent, a non-adjuvant QIV-SD from GlaxoSmithKline (GSK). Another control vaccine, FLUAD® Pediatric, an adjuvant TIV from Seqirus, was also evaluated because it is the only approved pediatric vaccine that has been evaluated in relevant efficacy trials. FLUAD® Pediatric is approved in Canada only for pediatric indications (6 months to under 2 years of age).

[0197] 1.2-Test Objectives safety Describe the safety of each dose of QIV-HD used in the study for 28 days after each vaccination, and any serious adverse events (SAEs) (including particularly noteworthy adverse events [AESIs]) throughout the study. immunogenicity • Describe the antibody response induced by each dose of QIV-HD used in the study compared to non-adjuvant QIV-SD, using hemagglutination inhibition (HAI) measurement methods. • Describe the antibody response induced by each dose of QIV-HD used in the study compared to non-adjuvant QIV-SD, using the viral serum neutralization (SN) assay method. • Describe the antibody response induced by the maximum tolerated dose of QIV-HD compared to adjuvant-treated TIV, using HAI and viral signaling assay methods.

[0198] 1.3 - Principal Investigator and Study Organization This trial was conducted at 16 sites in the United States and Canada. The principal investigator and any co-investigators at each site were coordinated by a single coordinating investigator.

[0199] Safety Management Team The Internal Safety Management Team (SMT) conducts an analysis of safety data during the trial period following the first vaccination (Early Safety Data Review [ESDR]).

[0200] Monitoring, data management, and statistical analysis Biostatistics, data management, monitoring, and medical writing are either outsourced to a contract research organization (CRO) or performed in-house by the clinical trial sponsor.

[0201] Laboratory analysis The tests were conducted in Sanofi Pasteur's Global Clinical Immunology (GCI) division or in external laboratories under the supervision of the GCI.

[0202] 1.4 - Independent Ethics Committee / Institutional Review Board Prior to the shipment of the investigational drug to the clinical trial site and the enrollment of the first subject, the clinical trial protocol, informed consent document (ICF), assent document, subject recruitment procedures, and all other information provided to the subject were approved by and / or received a favorable opinion from an appropriate independent ethics committee (IEC) or institutional review board (IRB).

[0203] In accordance with Good Clinical Practice (GCP) and local regulations, each principal investigator and / or sponsor was responsible for obtaining this approval and / or favorable opinion before commencing the trial.

[0204] 1.4.1 - Clinical Trial Planning Description of the overall test design and plan Test design QHD04 was a phase II, randomized, staged, modified double-blind, active-controlled, multicenter study conducted in 665 children aged 6 months to 17 years to evaluate the safety and immunogenicity of three doses of QIV-HD administered via the IM route compared to QIV-SD or adjuvanted TIV.

[0205] The trial was divided into 13 groups and enrolled in four stages. A graded age-decreasing and dose-increasing design was used for children aged 6 months to under 5 years. A dose-increasing design was also used for children aged 5 to 8 years, initiating enrollment to Stage 1. Children aged 9 to 17 years were enrolled in Stage 1 and randomized to receive all three dose formulations (i.e., 30 μg, 45 μg, and 60 μg HA / strain / dose). ESDRs were performed after visit (V)02 (8 days post-vaccination [D]) for children aged 6 months to under 5 years in Stages 1, 2, and 3, and after visit (V)02 (8 days post-vaccination [D]) for children aged 5 to 8 years in Stages 1 and 2. ESDRs for children aged 6 months to under 5 years were independent of those for children aged 5 to 8 years.

[0206] The 13 test groups were divided as follows: • Age (9 to 17 years old (i.e., from the 9th birthday to the day before the 18th birthday), 5 to 8 years old (i.e., from the 5th birthday to the day before the 9th birthday), 36 months to under 5 years old, 6 months to under 36 months old, or 6 months to under 24 months old) • Influenza vaccination history (previously vaccinated against influenza, previously not vaccinated against influenza, or both) • The vaccine administered (QIV-HD dose [30 μg, 45 μg, or 60 μg HA / strain / dose], non-adjuvant QIV-SD, and adjuvant TIV).

[0207] The test design is shown in Table 1A, and in Figures 1A-1D, 2A-2C, and 3.

[0208] Stage 1 included three age groups (36 months to under 5 years, 5 to 8 years, and 9 to 17 years) and was conducted in the United States: Participants aged 36 months to under 5 years (Group 1), who had previously received the influenza vaccine and those who had not, were randomized to receive either 30 μg HA / strain / dose of QIV-HD or unadjuvanted QIV-SD. Based on early safety data review, the trial was either stopped (Group 1 did not pass the safety review) or advanced to Stage 2. • Participants aged 5 to 8 years (group 9) who had previously received the influenza vaccine and those who had not were randomized to receive either 30 μg HA / strain / dose of QIV-HD or unadjuvanted QIV-SD. Based on early safety data review, enrollment in this age group will be discontinued (group 9 will not pass safety review) or the group will proceed to stage 2. Participants aged 9 to 17 years (hereinafter referred to as the 9-17 year old group) who had previously received the influenza vaccine and those who had not received it were divided into two groups (Group 12 and Group 13). Group 12 was enrolled first and randomized to receive either 30 μg or 45 μg HA / strain / dose of QIV-HD or unadjuvanted QIV-SD. Once enrollment for Group 12 was complete, participants in Group 13 were randomized to receive either 60 μg of QIV-HD or unadjuvanted QIV-SD. Participants aged 9 to 17 years did not undergo ESDR.

[0209] Stage 2 included three age groups (6 months to under 36 months, 36 months to under 5 years, and 5 to 8 years) and was conducted in the United States: • Participants aged 36 months to under 5 years (Group 2), who had previously received the influenza vaccine or were not vaccinated, were randomized to receive either 45 μg HA / strain / dose of QIV-HD or unadjuvanted QIV-SD. Participants aged 6 months to under 36 months (Group 3), who had previously received the influenza vaccine or were not vaccinated, were randomized to receive either 30 μg HA / strain / dose of QIV-HD or unadjuvanted QIV-SD. Based on early safety data review, the trial could be stopped (Group 3 did not pass safety review), skipped and proceeded to Stage 4 (Group 2 did not pass safety review), or proceeded to Stage 3 (both Group 2 and Group 3 passed safety review). • Participants aged 5 to 8 years (group 10) who had previously received the influenza vaccine and those who had not received it were randomized to receive either 45 μg HA / strain / dose of QIV-HD or unadjuvanted QIV-SD. Based on early safety data review, enrollment in this age group will be discontinued (group 10 will not pass safety review) or the group will proceed to stage 3.

[0210] Stage 3 included three age groups (6 months to under 36 months, 36 months to under 5 years, and 5 to 8 years) and was conducted in the United States: Group 4 (36 months to under 5 years of age) was randomized to either 60 μg HA / strain / dose of QIV-HD or unadjuvant-free QIV-SD; Group 5 (6 months to under 36 months of age) was randomized to either 45 μg HA / strain / dose of QIV-HD or unadjuvant-free QIV-SD. Based on early safety data review, the maximum dose with acceptable safety review (60 μg HA / strain / dose of QIV-HD) was determined and used in Stage 4. Participants aged 5 to 8 years (group 11), both those previously vaccinated with influenza and those who were not, were randomized to receive either 60 μg HA / strain / dose of QIV-HD or unadjuvanted QIV-SD.

[0211] Stage 4 included two age groups (6 months to under 36 months and 6 months to under 24 months) and was conducted in the United States (for subjects 6 months to under 36 months) and Canada (for subjects 6 months to under 24 months): Subjects aged 6 months to under 36 months who had not previously received an influenza vaccine (Group 6) and subjects aged 6 months to under 36 months who had previously received an influenza vaccine (Group 7) were randomized to receive either the maximum dose of QIV-HD (60 μg HA / strain / dose of QIV-HD) or unadjuvanted QIV-SD, with acceptable safety review. • Subjects aged 6 months to under 24 months (Group 8) who had not previously received the influenza vaccine were administered either QIV-HD (60 μg HA / strain / dose of QIV-HD) or adjuvanted TIV at the maximum dose subject to acceptable safety review.

[0212] 1.4.1 - Justification of the test design The QHD04 trial was designed to describe the safety of three different doses of QIV-HD in children aged 6 months to 17 years. The trial was also designed to describe the immunogenicity of the different doses of QIV-HD compared to unadjuvanted QIV-SD (Fluarix® Quadrivalent, approved in the U.S.) at all stages of the trial, and compared to adjuvanted TIV (FLUAD® Pediatric, approved in Canada) in stage 4 after the maximum acceptable dose of QIV-HD had been established.

[0213] Given the differing volumes of the three different doses of QIV-HD and the comparative vaccine, QHD04 was a staging, modified double-blind trial with open-label administrators at each study site. The administrators were not involved in any of the blinded trial evaluations (e.g., safety).

[0214] Since this was the first time QIV-HD had been administered to a pediatric population, an ESDR (Endoscopic Study Review) was conducted on subjects aged 6 months to 8 years prior to dose increases (30, 45, and 60 μg HA / strain / dose).

[0215] Given the mature immune systems in children aged 9 to 17 years, ESDR was not necessary for subjects aged 9 to 17 years prior to dose increases. To maintain randomization ratios across all age groups and thus allow for pooling of 30, 45, and 60 μg HA / strain / dose formulations across all age groups, subjects aged 9 to 17 years were randomized to receive 30 and 45 μg HA / strain / dose vaccines, separately from subjects aged 9 to 17 years who received the 60 μg HA / strain / dose formulation.

[0216] Because FLUAD Pediatric is the only approved pediatric vaccine with trials evaluating both HAI immunogenicity and relative efficacy data, a comparison with QIV-HD (maximum dose with acceptable safety) and adjuvanted TIV used in Stage 4 served as an indicator of expected vaccine efficacy.

[0217] 1.4.2 - Test Plan The test plan is summarized in the test procedure tables (Tables 2-4).

[0218] Vaccination All eligible subjects were randomized to receive one or two doses of either QIV-HD, Fluarix® Quadrivalent (unadjuvant-free QIV-SD), or FLUAD Pediatric® (adjuvant-free TIV). The dose of QIV-HD administered would depend on both the subject's age and the stage at which they were enrolled. • In group D0, subjects aged 9 to 17 years were given a single dose of either QIV-HD or a comparative vaccine. In a study (D0), subjects aged 6 months to 8 years who had previously received the influenza vaccine were given a single dose of either QIV-HD or a comparative vaccine. In subjects aged 6 months to 8 years who had not previously received an influenza vaccine, two doses of either QIV-HD or a comparative vaccine were administered. Each dose was given 28 days apart (on D0 and D28).

[0219] Of particular note is that the maximum dose administered with acceptable safety assessment in the previous stage determined the dose to be evaluated in Stage 4.

[0220] The vaccine was administered by open-label administrators at each facility.

[0221] Blood sample Participants were required to provide two or three blood samples, regardless of their registration stage: For subjects aged 9 to 17 years, pre-vaccination (baseline) blood samples will be provided on V01 (D0) and post-vaccination blood samples on V03 (D28 [+7 days]) for HAI and SN trials. Note: Two facility visits were scheduled for the 9- to 17-year-old group. However, to match the naming convention for the 6-month-to-8-year-old age group, the second visit is designated as V03. • Subjects aged 6 months to 8 years who had previously received the influenza vaccine provided pre-vaccination (baseline) blood samples in V01 (D0) and post-vaccination blood samples in V03 (D28 [+7 days]) for the HAI and SN studies. · Subjects aged 6 months to 8 years who had not been previously vaccinated against influenza provided pre-vaccination (baseline) blood samples at V01 (D0) and post-vaccination blood samples at V03 (D28[+7 days]) and V05 (28 days after V03[+7 days]) for the HAI and SN tests.

[0222] Note: Blood samples were collected before vaccination during any visit when the subject received vaccination.

[0223] Collection of safety data All subjects were observed for 30 minutes after vaccination, and any spontaneous reported systemic adverse events (AEs) that occurred during that time were recorded in the case report form (CRF) as immediate, spontaneously reported systemic AEs.

[0224] Reactions from non-spontaneous reports were collected up to 7 days after each vaccination, and AEs from spontaneous reports were collected up to D28 (V03) for subjects receiving one dose and up to D56 (V05) for subjects receiving two doses. Serious adverse events (SAEs) and especially notable adverse events (AESIs) were collected throughout the study (from D0 to approximately 6 months after the last vaccination). AESIs were captured as SAEs. These included new occurrences of Guillain-Barré syndrome (GBS), encephalitis / myelitis (including transverse myelitis), Bell palsy, seizures, optic neuritis, and brachial neuritis.

[0225] Subjects / parents / guardians were requested to immediately notify the facility of any potential SAE (including AESI) at any time during the study.

[0226] Research staff contacted subjects aged 9 to 17 years or the subjects' parents / guardians by phone on D8 (+2 days) after vaccination to identify whether the subject had experienced any unreported SAE and reminded the subject / parents / guardians to bring the log card filled in at V03 (D28[+7 days]). Research staff reviewed the safety data from D0 to V03 with the subject at V03.

[0227] Participants aged 6 months to 8 years returned to the facility on day 8 (+3 days) after each vaccination. Staff reviewed recorded involuntary reactions and voluntary AEs to determine if any participants experienced any unreported SAEs and AESIs. Staff reviewed safety data with participants / partners / guardians at each visit. Staff also reminded participants / partners / guardians to bring completed log cards to subsequent visits.

[0228] Using an interactive response (IRT) system, subjects were randomly assigned to the test product, and a subject number was assigned to each group.

[0229] Electronic data acquisition (EDC) was used for data collection.

[0230] Review of safety data The trial was divided into four stages (Section 1.5). The ESDR was conducted on subjects aged 6 months to 8 years. The ESDR was performed by SMT following the collection of safety data at V02 (approximately 8 days after vaccination) in stages 1, 2, and 3. Enrollment of subjects to the next stage was initiated if the safety review results were satisfactory.

[0231] 1.4.3 - Visit Procedure Visit Procedure Visit 1 (Day 0): Enrollment, randomization, blood sampling, and vaccination - for all subjects

[0232] The principal investigator or co-investigator: 1) Provide information about the test to the subject and / or the subject's parent / guardian. 2) Obtain informed consent and assent (for subjects aged 7 to 17), and answer all questions to ensure that subjects and / or their parents / guardians are informed of all aspects of the study relevant to their decision to participate. 3) After the subject or their parent / guardian signs and dates the document, date and sign the ICF (and the Ascent document for subjects aged 7 to 17). Keep the original and give the subject or their parent / guardian a signed copy. 4) Check all inclusion and exclusion criteria through physical examination and interviews of the subject and / or the subject's parent / guardian. If a subject is ineligible, the subject identification will be recorded only in a specific document titled “Recruitment Record,” and the CRB will not fill it out. 5) Collect relevant demographic information (e.g., date of birth, sex, ethnicity, and race). 6) For women of childbearing age, a urine pregnancy test will be performed. 7) Obtain oral information regarding the patient's medical history. 8) Obtain information regarding seasonal influenza vaccination and any influenza diagnosis, such as: For individuals who have not previously received an influenza vaccine, it will be confirmed that they have never received any seasonal influenza vaccine since birth and have never been diagnosed with influenza. i. In the U.S. facilities, in accordance with the Advisory Committee on Immunization Practices (ACIP) guidelines, this trial will consider subjects aged 6 months to 8 years who have never received an influenza vaccine or who have not received at least two doses of seasonal influenza vaccine during the previous influenza season as "previously unvaccinated subjects" at the time of enrollment, and therefore these subjects will receive two doses of the study vaccine at least 28 days apart. Subjects whose vaccination history is unknown at the time of enrollment will also be considered "previously unvaccinated subjects" and will similarly receive two doses of the study vaccine at least 28 days apart. ii. For Canadian facilities, in accordance with the National Advisory Committee on Immunization (NACI) recommendations, this trial will consider subjects aged 6 months to under 24 months who have never received an influenza vaccine in the previous influenza season as "previously unvaccinated subjects" at the time of enrollment, and therefore these subjects will receive two doses of the study vaccine at least 28 days apart. Subjects who have previously received at least one dose of any influenza vaccine will not be considered "previously unvaccinated subjects." For individuals who have previously received the influenza vaccine, the date (year and month) of their last seasonal influenza vaccination is obtained. i. In the U.S. facilities, in accordance with ACIP guidelines, this trial will consider subjects aged 6 months to 8 years who have received at least two doses of seasonal influenza vaccine during the previous influenza season as "previously vaccinated subjects" at the time of enrollment, and therefore these subjects will receive only one dose of the study vaccine. 9) For subjects aged 6 to 12 months, if the mother received an influenza vaccine during pregnancy or during routine breastfeeding, information regarding that vaccination will be obtained. 10) Collect information on concomitant medications that must be reported. 11) For each standard site-specific immunization procedure, perform and document a targeted physical examination, and record body temperature (tympanic and temporal artery thermometers should not be used) in the source document. 12) Call the IRT for the assignment of 12-digit target numbers, randomization, and allocation of dosing numbers. 13) Take a blood sample of approximately 5 mL for processing (blood collection should be done before vaccination). Note: If it is not possible to extract a 5 mL blood sample, a volume of less than 5 mL may be obtained. Note: If the subject's parent / guardian withdrew consent before blood collection (before any invasive procedure was performed), the subject was not vaccinated and was considered to have withdrawn from the study. Note: If attempts to draw blood (if multiple) were unsuccessful (3 attempts), the subject was included in the study and vaccinated.

[0233] Non-blinded eligible study staff: 14) Administer the appropriate vaccine intramuscularly into the anterolateral thigh muscle or deltoid muscle of the upper arm as needed (the vaccine must be administered on the opposite side from blood collection). 15) Record the injection site / side / pathway / administration number and attach the corresponding removable label to the source document.

[0234] The principal investigator or sub-investigator: 16) Keep the subject under medical supervision for at least 30 minutes after injection and report to the source document whether any AE occurred or not. 17) Give the subject or the subject's parent / guardian a diary card (DC) 1 for recording any injection site reactions and systemic AEs, along with instructions for filling it out, including an explanation of the definition and use of the intensity scale for AE collection. 18) Give the subject or the subject's parent / guardian a ruler for measuring the size of any injection site reactions, a thermometer for measuring body temperature, and instructions on how to use them. 19) Remind the subject or the subject's parent / guardian to bring DC1 back when returning at V02. For subjects aged 9 to 17, schedule a phone call at D8. 20) Remind the subject or the subject's parent / guardian to immediately notify the facility in case of any SAE / AESI that may occur at any time during the study. 21) Enter relevant information about this visit in the CRB form.

[0235] Phone call (8 [+2] days after visit 1): Collection of safety information - for subjects aged 9 to 17 If the phone call falls on a weekend or public holiday, the call will be scheduled for the next business day.

[0236] The principal investigator or co-investigator: 1) Record relevant information regarding the subject's health status in a written telephone contact. Follow instructions for reporting any SAEs that occur. 2) Instruct the subject or their parent / guardian to do the following: Fill in the remaining pages of DC1 and bring the completed log to V03 (D28 [+7 days]). • Notify the facility in the event of a SAE (Surface-Affected Engagement).

[0237] Visit 2 (8 [+3] days after Visit 1): Collection of safety information - for subjects aged 6 months to 8 years. If Visit 2 falls on a weekend or public holiday, the visit can be scheduled for the next business day.

[0238] The principal investigator or co-investigator: 1) Review the information in DC1 with the subject or their parent / guardian (for clarity, content, and completeness), and, if necessary, clarify with the subject or their parent / guardian any AEs, medications, or SAEs that have occurred since V01. If an SAE occurs, follow the instructions in this specification for reporting it. 2) Record safety data from D0 to D7 in the CRB. 3) Instruct the subject or their parent / guardian to do the following: • Fill in the remaining pages of DC1 and bring the completed logbook to V03. • Notify the facility in the event of a SAE (Surface-Affected Engagement).

[0239] Visit 3 (28 [+7] days after Visit 1) - for subjects aged 9 to 17 years, and for subjects aged 6 months to 8 years who have previously received the influenza vaccine. The group aged 9 to 17 was scheduled for two facility visits. However, to match the naming convention for the 6-month to 8-year-old age group, the second visit was designated V03.

[0240] The principal investigator or co-investigator: 1) Review and collect DC1 information with the parent / guardian (for clarity, content, and completeness), and, where necessary, clarify with the parent / guardian any AEs, medications, or SAEs that have occurred since a phone call (for subjects aged 9 to 17 years) or V02 (for subjects aged 6 months to 8 years who have previously received the vaccine). 2) Take approximately 5 mL of blood sample for processing. i. If it is not possible to extract a 5 mL blood sample, a volume of less than 5 mL may be obtained. ii. If the attempt(s) to collect blood (multiple attempts) was unsuccessful (up to three attempts), the parent / guardian was given the opportunity to bring their child to the study facility for another attempt within the visiting window. If a blood sample could not be obtained, the reason was recorded on the blood collection page of the CRB. In this case, the subject was tracked for safety in the study. 3) Provide memory aids (MA) to the subject / parent / guardian and review the instructions for their use. 4) Instruct the subject / parent / guardian to immediately notify the facility in the event of any SAE that may occur at any time during the trial. 5) Schedule a 6-month safety follow-up phone call. 6) Record all relevant information obtained in the CRB. 7) Record the completion of the CRB.

[0241] Visit 3 (28 [+7] days after Visit 1) - for subjects aged 6 months to 8 years who have not previously received the influenza vaccine. The principal investigator or co-investigator: 1) Review and collect DC1 information with the parent / guardian (for clarity, content, and completeness), and, if necessary, clarify with the parent / guardian any AEs, medications, or SAEs that have occurred since V02. 2) If necessary, conduct targeted physical examinations. 3) Review temporary and definitive contraindications to vaccination. 4) Take a blood sample of approximately 5 mL (blood collection should be done before vaccination). i. If it is not possible to extract a 5 mL blood sample, a volume of less than 5 mL may be obtained. ii. If the attempt to collect blood(s) is unsuccessful (up to three attempts), the parent / guardian will be given the opportunity to bring their child to the testing facility for one more attempt within the visiting window. If a blood sample cannot be obtained, the reason will be recorded on the blood collection page of the CRB. In this case, the subject will remain in the test and will be vaccinated after all attempts to collect blood have been completed.

[0242] Open-label qualified research staff: 5) Call IRT and obtain the unique dosage number. 6) Administer the appropriate vaccine intramuscularly to the anterolateral thigh muscle or deltoid muscle of the upper arm, if necessary (the vaccine must be administered on the opposite side from where the blood was drawn). 7) Record the injection site / side / route / dosage number in the source document and attach a removable corresponding label to the source document.

[0243] The principal investigator or co-investigator: 8) Keep the subject under medical supervision for at least 30 minutes after injection and report in the source document whether or not any adverse events (AEs) occurred. 9) Provide the subject / parent / guardian with a DC2 to record any injection site reactions and systemic AEs, along with instructions for use to fill it out, including an explanation of the definition and use of the intensity scale for collecting AEs. 10) Instruct the subject / parent / guardian to bring DC2 with them when returning via V04. 11) Instruct the subject / parent / guardian to immediately notify the facility in the event of any SAE that may occur at any time during the trial. 12) Complete the relevant CRB documents regarding this visit.

[0244] Visit 4 (8 [+3] days after Visit 3) - For subjects aged 6 months to 8 years who have not previously received the influenza vaccine. The principal investigator or co-investigator: 1) Review the information in DC2 with the subject / parent / guardian (for clarity, content, and completeness), and, if necessary, clarify with the parent / guardian any AEs, medications, or SAEs that occurred after V03. 2) Record safety data for days D28 to D35 in the CRB. 3) Instruct the subject / parent / guardian to do the following: • Fill in the remaining pages of DC2 and bring them to V05. • Notify the facility in the event of a SAE (Surface-Affected Engagement).

[0245] Visit 5 (28 [+7] days after Visit 3) - for subjects aged 6 months to 8 years who have not previously received the influenza vaccine. The principal investigator or co-investigator: 1) Review and collect DC2 information (for clarity, content, and completeness) with the parent / guardian, and, where necessary, clarify with the subject / parent / guardian any AEs, medications, or SAEs that have occurred since V04. If an SAE occurs, follow the instructions in this specification for reporting it. 2) Take approximately 5 mL of blood sample for processing. i. If it is not possible to extract a 5 mL blood sample, a volume of less than 5 mL may be obtained. ii. If the attempt(s) to collect blood (multiple attempts) is unsuccessful (up to three attempts), the parent / guardian will be given the opportunity to bring their child to the testing facility for one more attempt within the visiting window. If a blood sample cannot be obtained, the reason will be recorded on the blood collection page of the CRB. In this case, the subject will remain in the test. 3) Provide MA to the target / parent / guardian and review the instructions for its use. 4) Instruct the subject / parent / guardian to immediately notify the facility in the event of any SAE that may occur at any time during the trial. 5) Schedule a 6-month safety follow-up phone call. 6) Record all relevant information obtained in the CRB. 7) Record the completion of the CRB.

[0246] Safety follow-up phone call - approximately 6 months after the last vaccination: SAE collection 1) Inquire about new SAE cases and conduct follow-up investigations related to SAEs. If an SAE occurs, inquire whether the person has received any vaccinations or other medications since the last contact. 2) Explain that this will be the final contact with the facility regarding this trial (excluding subjects with SAEs requiring further follow-up, as shown below).

[0247] If the initial attempt to complete a final phone call is unsuccessful, at least two separate additional attempts will be made on different days to contact these subjects. All attempts will be documented in the subject's source notes. If contact cannot be established after at least three documented attempts, the subject will be classified as untraceable.

[0248] The following are exceptions regarding the final phone call: • Those who voluntarily withdraw • Cases that have been classified as untraceable so far

[0249] Follow-up studies of subjects with related adverse events (AEs) or AEs that lead to discontinuation of trials / vaccination: Participants who experience an AE (whether serious or not) during the study will be followed up until their condition improves, stabilizes, or becomes chronic (even after the participant's participation in the study ends) if any of the following conditions are met: The principal investigator believes that the adverse event (AE) is related to the administered product. • An adverse event (AE) caused the suspension of the trial or vaccination program in question.

[0250] 1.4.4-Early Safety Data Review The safety of the investigational drug was continuously monitored by the sponsor. An ESDR was conducted with the aim of enabling a careful, stepwise approach to vaccine administration. A stepwise dose-increase approach was applied to subjects aged 5 to 8 years (30 μg, 45 μg, and 60 μg HA / strain / dose). A stepwise age-decreasing vaccination approach was adopted for subjects aged 36 months to under 5 years, along with a pre-vaccination ESDR and stepwise dose-increase for subjects aged 6 months to under 36 months. The ESDR was conducted in subjects aged 6 months to 8 years following V02.

[0251] The ESDR for this trial is scheduled to take place after the age groups from 6 months to 8 years in each stage have been vaccinated and safety data for days 0 to 7 post-vaccination have been provided using the data collection methods described in the protocol. The ESDR was not performed for subjects aged 9 to 17 years.

[0252] Enrollment of subjects was suspended during each ESDR. However, subjects already enrolled between 6 months and 8 years of age required two doses of vaccination due to their previous vaccination status and were to receive their second dose on D28 as scheduled, although this may have been prior to the ESDR. Enrollment of subjects to subsequent or appropriate stages was to be resumed after satisfactory safety review. Study visits were continued to be tracked for enrolled subjects within each activity stage (i.e., subjects completed their scheduled visits) according to the study procedure table.

[0253] The collected safety data was entered into the CRB and summarized by the sponsor in a blinded format. Review was conducted by the sponsor during the SMT meeting. It is understood that this review was based on preliminary data not subject to validation or database locking. (The usual and ongoing processes for monitoring safety signals outside of those specified in the early interim safety analysis defined in the protocol continued without modification.)

[0254] The following safety parameters were evaluated as part of the early safety review: • Immediate response • Involuntary reports of injection site and systemic reactions • Voluntary reporting of AE • SAE (including AESI)

[0255] During the review process, registration was suspended and data was examined for the following occurrences: • SAEs (including AESIs) that the principal investigator and sponsor believe are related to vaccination. • More than 10% of participants experience a Grade 3 fever within 7 days of vaccination.

[0256] If any of the above criteria are met, a decision will be made on whether or not to allow the resumption of registration for the exam.

[0257] If necessary, case-opening may be implemented.

[0258] 1.5- Enrollment and retention of the test population 1.5.1 - Recruitment Procedure Participants will be recruited from the general public.

[0259] The documentation of the consent process should be recorded in the source documentation.

[0260] 1.5.2 - Screening Criteria There are no screening criteria other than inclusion and exclusion criteria.

[0261] 1.5.3 - Inclusion Criteria In order for an individual to be eligible for trial registration, it must meet all of the following criteria: 1) The child must be between 6 months and 17 years old on the day of inclusion ("6 months to 17 years old" means from 6 months of age until the day before the 18th birthday). 2) The assent document must be signed and dated by the subject (ages 7 to 17), and the informed consent document must be signed and dated by a parent(s) or guardian(s), and, where required by local regulations, by an independent witness. 3) The subject and their parent / guardian must be able to attend all scheduled visits and comply with all examination procedures. 4) For those under 24 months of age: Born at full term (longer than or equal to 37 weeks) and / or with a birth weight greater than or equal to 2.5 kg.

[0262] 1.5.4-Exclusion criteria Individuals meeting any of the following criteria were excluded from the trial registration:

[0263] [Table 10-1] [Table 10-2]

[0264] 1.5.6 - Medical History Prior to enrollment, participants were assessed for both past and ongoing existing conditions and illnesses. A significant (clinically relevant) medical history (reported as a diagnosis) was collected in the CRB, including conditions / illnesses that participants were or had been followed by a physician, or that may recur during the course of the study or lead to SAEs or recurrent outpatient visits. The significant medical history section of the CRB included a core list of physical systems and disabilities that could be used to facilitate comprehensive reporting, as well as space for reporting specific conditions and illnesses.

[0265] For each state, the collected data was limited as follows: • Diagnosis (This is preferable for reporting signs and symptoms) • Status at the time of registration

[0266] Dates, medications, and physical characteristics are not recorded, and the collected information is not coded. The purpose is to aid in the later interpretation of safety data collected during the trial.

[0267] 1.5.7 - Contraindications for subsequent vaccination The contraindication applies only to individuals who have not previously received the influenza vaccine and who will receive two doses of the vaccine 28 (+7) days apart.

[0268] 1.5.7.1 - Temporary Contraindications If a participant experienced any of the conditions listed below, the principal investigator postponed further vaccination until the condition improved. The postponement still had to be within the vaccination timeframes outlined in the study procedure tables (Tables 2-4). • Febrile illness (body temperature of ≥38.0°C [≥100.4°F]) or moderate or severe acute illness / infection on the day of vaccination, as determined by the principal investigator.

[0269] 1.5.7.2 - Critical Contraindications The following criteria apply to subjects who had never received any influenza vaccine before the start of the trial and who received two influenza vaccine injections during the trial (one in V01 and one in V03). If a subject experienced any of the conditions listed below, the principal investigator discontinued vaccination. • D01: Anaphylaxis or other serious allergic reaction to the previous dose of vaccine. • D02: The patient has received some form of immunoglobulin, blood, or blood-derived product between V01 and V03. D03: Known or suspected congenital or acquired immunodeficiency; or immunosuppressive therapy such as anticancer chemotherapy or radiotherapy since the last visit; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than two consecutive weeks since the last visit). D04: Thrombocytopenia or bleeding disorders that may be contraindications for IM vaccination, based on the judgment of the principal investigator. • D05: A chronic disease that, in the opinion of the principal investigator, may be in a stage that could prevent the conduct or completion of the trial. • D06: The occurrence of any condition (including GBS, clinically significant growth retardation, neurological disorders, seizure disorders, hepatitis B, or hepatitis C) in the opinion of the principal investigator that would pose a health risk to the subject or would interfere with the evaluation of the test vaccine. • D07: Any SAE related to the trial vaccine, following the previous trial vaccination, based on the judgment of the principal investigator.

[0270] Subjects with critical contraindications (if any) were not vaccinated with V03, but were followed up for safety and immunogenicity assessments as defined in the study, where applicable.

[0271] In the event of a regional or national immunization program with a pandemic influenza vaccine or other vaccine, subjects who received the pandemic influenza vaccine or other vaccine at any point during the trial did not drop out of the trial.

[0272] 1.5.8 - Conditions for Withdrawal The subject / parents / guardians have been notified that they have the right to withdraw from the exam at any time. The subject may withdraw from the exam under the following circumstances: • Due to safety concerns or material non-compliance with the clinical trial protocol (based on the judgment of the principal investigator), the participant may withdraw without permission, at the discretion of the principal investigator or sponsor. • Dropped out at the request of the subject / parent / guardian.

[0273] The principal investigator determined whether the voluntary withdrawal (if any) was due to safety concerns (in which case the reason for discontinuation would be noted as an "adverse event") or for other reasons.

[0274] The members who withdrew were not replaced.

[0275] 1.5.9 - Untrackable Procedure In cases where a subject does not return for follow-up, reasonable documented efforts (i.e., documented telephone calls and certified mail) will be made to locate or recall the subject, or at least determine their health status with due respect to their rights.

[0276] 1.5.10 - Classification of subjects for which the test should be discontinued For any subject whose trial is terminated before completion, the most significant reason for early termination will be documented to the CRB. The reasons are listed below, from most significant to least significant:

[0277] [Table 11]

[0278] 1.5.11 - Follow-up investigation of the cancellation The facility will complete all scheduled safety follow-ups and contact any subject or parent / guardian of any subject whose trial was prematurely terminated due to an adverse event (AE), protocol deviation, or loss of eligibility, including a critical contraindication. The follow-up period in case of discontinuation is six months after the last vaccination.

[0279] If the reason for early termination is untraceable for a subject, or if the subject / parent / guardian withdraws their informed consent and specifies that they do not wish to be contacted again, and this is documented in the source document, the facility will not attempt to obtain further safety information.

[0280] If the subject's status at the end of the trial is "departure by subject or parent / guardian," the facility will attempt to contact them during the 6-month follow-up period unless they specify that they do not wish to be contacted again, and this is documented in the source document.

[0281] 1.5.14 - Pregnancy follow-up and reporting Pregnancy is an exclusion criterion for enrollment in this study; however, participants may become pregnant during their participation. In the event of pregnancy, if at least one dose of the study vaccine(s) has been administered, the participant will not be discontinued from the study. However, participants were followed up for safety assessment (and may be followed up for immunogenicity assessment where applicable).

[0282] All pregnancies will be reported if they occur during the study or the 6-month follow-up period.

[0283] While pregnancy itself is not considered an AE, any complications during pregnancy are considered AEs and may in some cases be considered SAEs. Spontaneous miscarriage, blighted ovum, fetal death, stillbirth, and congenital abnormalities reported in the newborn are always considered SAEs, and information should be provided to the Global Drug Safety Monitoring (GPV) unit regardless of when the SAE occurred (e.g., even after the trial has ended).

[0284] 1.6 - Identification of the investigational product 1.6.1. Identification of Test Product 1 The QIV-HD clinical trial is a split-virion quadrivalent influenza vaccine (30 μg HA / strain) containing virus strains selected by the WHO (VRBPAC in the US) for the NH2018-2019 influenza season. This vaccine contains two type A antigens (H1N1 and H3N2) and two type B antigens (derived from the Yamagata and Victoria lineages, respectively). Each pre-filled syringe contains a total of 120 μg of HA antigen per 0.35 mL dose, supplied in a sterile suspension for IM injection.

[0285] The QIV-HD vaccine is thimerosal-free and manufactured from influenza viruses grown in fertilized chicken eggs.

[0286] 1.6.1.1 - Composition of Test Product 1 Each 0.35 mL dose of vaccine contains the following components: (The strain is based on WHO [VRBPAC in the US] recommendations for the 2018-2019 NH influenza season):

[0287] [Table 12]

[0288] [Table 13]

[0289] Preservatives are not used in the manufacture of QIV-HD.

[0290] 1.6.1.2 - Manufacturing and administration of test product 1 The vaccine should be supplied in a pre-filled single-dose syringe and shaken before use. The vaccine should be administered transmuscularly into the anterolateral thigh muscle, or, where appropriate, the deltoid muscle of the upper arm. When injecting the vaccine into the arm, it should be administered to the arm opposite to the one from which blood was drawn prior to vaccination.

[0291] All test products shall be visually inspected before administration for cracks, broken seals, correct labeling of contents, and foreign particulate matter and / or discoloration, whenever the solution and container allow. If any of these conditions are present, this vaccine should not be administered. An alternative dose should be used.

[0292] To ensure the safety of the subjects, they were observed for 30 minutes after each vaccination, and any reactions during this period were documented during CRB. In the event of anaphylactic reactions, vasovagal reactions, or other immediate allergic reactions, appropriate medical intervention and emergency administration, including epinephrine (1:1000), was available at the site.

[0293] 1.6.1.3 - Dosage selection and timing of test product 1 The vaccination schedule will follow standard practice for annual influenza vaccinations for individuals who have previously received the influenza vaccine, those who have not received the influenza vaccine, and those aged 9 to 17 years.

[0294] 1.6.2 - Identification of Test Product 2 The QIV-HD clinical trial is a split-virion quadrivalent influenza vaccine (45 μg HA / strain) containing virus strains selected by the WHO (VRBPAC in the US) for the NH2018-2019 influenza season. This vaccine contains two type A antigens (H1N1 and H3N2) and two type B antigens (derived from the Yamagata and Victoria lineages, respectively). Each pre-filled syringe contains a total of 180 μg of HA antigen per 0.52 mL dose, supplied in a sterile suspension for IM injection.

[0295] The QIV-HD vaccine is thimerosal-free and manufactured from influenza viruses grown in fertilized chicken eggs.

[0296] 1.6.2.1 - Composition of Test Product 2 Each 0.52 mL dose of vaccine contains the following components: (The strain is based on WHO [VRBPAC in the US] recommendations for the 2018-2019 NH influenza season):

[0297] [Table 14]

[0298] [Table 15]

[0299] Preservatives are not used in the manufacture of QIV-HD.

[0300] 1.6.2.2 - Manufacturing and administration of test product 2 The procedure for manufacturing and administering test product 2 is the same as the procedure described for test product 1.

[0301] 1.6.2.3 - Dosage selection and timing of test product 2 The dosage selection and timing for Investigational Product 2 are the same as those described for Investigational Product 1.

[0302] 1.6.3 - Identification of Test Product 3 The QIV-HD clinical trial is a split-virion quadrivalent influenza vaccine (60 μg HA / strain) containing virus strains selected by the WHO (VRBPAC in the US) for the NH2018-2019 influenza season. This vaccine contains two type A antigens (H1N1 and H3N2) and two type B antigens (derived from the Yamagata and Victoria lineages, respectively). Each pre-filled syringe contains a total of 240 μg of HA antigen per 0.7 mL dose, supplied in a sterile suspension for IM injection.

[0303] The QIV-HD vaccine is thimerosal-free and manufactured from influenza viruses grown in fertilized chicken eggs.

[0304] 1.6.3.1 - Composition of Test Product 3 Each 0.7 mL dose of vaccine contains the following components: (The strain is based on WHO [VRBPAC in the US] recommendations for the 2018-2019 NH influenza season):

[0305] [Table 16]

[0306] [Table 17]

[0307] Preservatives are not used in the manufacture of QIV-HD. 1.6.3.2 - Manufacturing and Administration

[0308] The procedure for manufacturing and administering test product 3 is the same as the procedure described for test product 1.

[0309] 1.6.3.3 - Dose selection and timing The dosage selection and timing for Investigational Product 3 are the same as those described for Investigational Product 1.

[0310] 1.6.4 - Identification of Control Product 1 Fluarix® Quadrivalent: Inactivated influenza vaccine (GlaxoSmithKline Biologicals, Dresden, Germany) • Form: Liquid solution · Dose: 0.5mL • Route: IM

[0311] 1.6.4.1 - Composition of Control Product 1 Each 0.5 mL dose contains 15 μg of HA for each of the following strains: The strain is based on WHO (VRBPAC in the US) recommendations for the 2018-2019 NH influenza season.

[0312] [Table 18]

[0313] [Table 19]

[0314] Fluarix Quadrivalent does not contain preservatives.

[0315] 1.6.4.2 - Manufacturing and administration of control product 1 Fluarix® Quadrivalent was manufactured and administered in accordance with the manufacturer's instructions for use (see, for example, Fluarix® Quadrivalent [Instructions for Use], GlaxoSmithKline Biologicals (Dresden, Germany)).

[0316] 1.6.4.3 - Dosage selection and timing for control product 1 Fluarix® Quadrivalent was administered as a single 0.5 mL dose to a randomized group of subjects in groups 1-7 and 9-13. Subjects aged 9-17 years and those aged 6 months-8 years who had previously received the influenza vaccine were administered in V01, and subjects aged 6 months-8 years who had not previously received the influenza vaccine were administered in V01 and V03.

[0317] 1.6.5 - Identification of Control Product 2 FLUAD® Pediatric: Influenza vaccine, surface antigen, inactivated, with MF59C.1 adjuvant added (Seqirus UK Limited, Maidenhead, UK) • Form: Liquid solution · Dose: 0.25mL • Route: IM

[0318] 1.6.5.1 - Composition of Control Product 2 Each 0.25 mL dose contains 7.5 μg of HA from one of the following strains: The strains are based on WHO (NACI in Canada) recommendations for the 2018-2019 NH influenza season.

[0319] [Table 20]

[0320] [Table 21]

[0321] FLUAD® Pediatric is formulated using adjuvant MF59, an oil-in-water emulsion of squalene oil.

[0322] FLUAD® Pediatric is preservative-free.

[0323] 1.6.5.2 - Manufacturing and administration of control product 2 FLUAD® Pediatric was manufactured and administered according to the manufacturer's product monograph (FLUAD Pediatric® [product monograph], Seqirus UK Limited (Maidenhead, UK)).

[0324] 1.6.5.3 - Dosage selection and timing for control product 2 FLUAD® Pediatric will be administered as a single dose of 0.25 mL to a group of subjects randomized in Group 8 in V01 and V03.

[0325] 1.6.6 - Product Storage At the facility, products will be kept in a secure location with restricted access. Vaccines will be stored in a refrigerator at a temperature of +2°C to +8°C and will not be frozen. The temperature will be monitored and documented for the entire time the vaccine is in the testing facility. In the event of accidental freezing or disruption of the cold chain distribution system, the vaccine must not be administered and must be isolated.

[0326] 1.6.7 - Blinding and Code Deciphering Procedures This study is designed as a graded, modified, double-blind trial using the following scales to ensure data integrity: • The vaccine is administered by open-label, qualified test staff members who are not involved in safety evaluations or other test evaluations. • The principal investigator (or their representative) responsible for safety assessment, the trial staff collecting safety data, and the researchers analyzing blood samples do not know which product was administered. • The subject / parent / guardian is unaware of which product was administered. To maintain blinding for the subject / parent / guardian, the vaccine syringe label is covered with an appropriate substance before administration.

[0327] The principal investigator responsible for safety assessment will not be present at the vaccination session, but will be available to respond in case of an emergency (e.g., anaphylactic shock).

[0328] Each vaccine syringe is identified using a dose number for the purpose of randomization, vaccination, and recording of administered vaccines. Dose numbers are randomly assigned to QIV-HD and commercially available vaccine syringes. The IRT supplier is responsible for identifying subjects and providing the dose numbers that registered subjects will receive. Subjects / parents / guardians, the principal investigator, members of the clinical trial staff collecting safety data, and experimenters analyzing blood samples are not informed of their group assignments. Individuals responsible for manufacturing / administering the vaccine are not permitted to collect any safety / serological data.

[0329] Code decryption of an AE event is permitted only if identifying the administered vaccine could influence the treatment in question. Code decryption is limited to the subject experiencing the AE.

[0330] 1.6.8 - Randomization and Assignment Procedure Regarding the randomization of dose numbers, the trial sponsor or designer supplies a computer-generated randomization list, which is used for labeling and packaging.

[0331] This study was randomized and modified to be double-blind across all treatment groups. On the day of registration, participants who met all inclusion criteria, did not meet any exclusion criteria, and completed the informed consent process were randomly assigned to receive the following vaccinations: In the United States, for subjects aged 9-17 years who are registered during Stage 1, previously vaccinated with influenza, and unvaccinated, either QIV-HD or 45 μg of HA / strain / dose in a 3:3:1 ratio, or Fluarix® Quadrivalent. In the United States, for subjects aged 9-17 years who are registered during Stage 1, have previously received the influenza vaccine, and have not received the vaccine, either 60 μg HA / strain / dose of QIV-HD or Fluarix® Quadrivalent in a 1:1 ratio. In the United States, for subjects aged 36 months to 8 years who are registered during Stage 1, have previously received the influenza vaccine, and have not received the vaccine, either QIV-HD or Fluarix® Quadrivalent at a ratio of 3:1, with a dose of 30 μg HA / strain / dose. In the United States, for subjects aged 36 months to 8 years who are registered during Stage 2, previously vaccinated with influenza, and unvaccinated, either QIV-HD or Fluarix® Quadrivalent at a 3:1 ratio of 45 μg HA / strain / dose. In the United States, for subjects aged 6 to under 36 months who are registered during Stage 2, have previously received the influenza vaccine, and have not received the vaccine, either 30 μg HA / strain / dose of QIV-HD or Fluarix® Quadrivalent. In the United States, for subjects aged 36 months to 8 years who are registered during Stage 3, previously vaccinated with influenza, and unvaccinated, either 60 μg HA / strain / dose of QIV-HD (the highest dose of QIV-HD) or Fluarix® Quadrivalent was administered in a 1:1 ratio. In the United States, for previously vaccinated subjects aged 6–36 months registered at Stage 4, either QIV-HD or Fluarix® Quadrivalent at the highest acceptable safety dose, in a 1:1 ratio. In the United States, for previously unvaccinated subjects aged 6–36 months enrolled at Stage 4, either QIV-HD or Fluarix® Quadrivalent at the highest acceptable safety dose in a 1:1 ratio. In Canada, for previously unvaccinated subjects aged 6 to under 24 months who are registered at Stage 4, either QIV-HD or FLUAD Pediatric at the highest acceptable safety dose, in a 1:1 ratio.

[0332] Facility staff connect to the IRT, enter identification and security information, and verify the minimum amount of data provided in response to IRT prompts. The IRT provides group assignments, which facility staff are then asked to verify. Stratified randomization is applied to all enrolled subjects in each group, stratified by their previous influenza vaccination status and country. Due to the small sample size in each group, facilities do not constitute stratification for randomization. The allocation ratios between the trial HD vaccine and the comparator are as follows: 3:1 ratio for groups 1, 2, 3, 5, 9, and 10; 3:3:1 ratio for group 12; and 1:1 ratio for groups 4, 6, 7, 8, 11, and 13. If a subject is ineligible to participate in this trial, this information is limited to recording it in the subject recruitment log.

[0333] [Table 22]

[0334] 1.6.9 - Concomitant medications and other treatments At registration, any medications and other treatments you are currently taking (e.g., blood products), as well as any new medications prescribed for any new medical conditions / adverse events during your participation in the study, must be recorded in the source document.

[0335] Reportable medications are collected at the CRB from the date of the first vaccination until the end of the involuntary and voluntary follow-up periods (from D0 to D28 for subjects aged 9–17 years and subjects aged 6 months–8 years who have previously received the influenza vaccine, and from D0 to D56 for subjects aged 6 months–8 years who have not previously received the influenza vaccine).

[0336] Reportable medicines include medicines that affect, or may affect, the consistency of safety information collected after any vaccination and / or immune response to vaccination. Three standard classifications of reportable medicines are defined below: • Classification 1: Medications that affect or may affect safety assessments (e.g., antipyretics, analgesics, and non-steroidal anti-inflammatory drugs [NSAIDs]). • Classification 2: Pharmaceuticals that affect or may affect the immune response (e.g., other vaccines, blood products, immunosuppressants, immunomodulators with immunosuppressive properties, antiproliferative drugs such as DNA synthesis inhibitors). • Classification 3: Medications that affect or may affect both safety and immune response (e.g., steroids / corticosteroids).

[0337] 1.7 - Sample Management Blood samples for evaluating antibody responses are collected on V01 and V03 (D28 [+7 days]) for subjects aged 9–17 years and subjects aged 6 months–8 years who have previously received the influenza vaccine, and on V01, V03, and V05 for subjects aged 6 months–8 years who have not previously received the influenza vaccine.

[0338] 1.7.1 - Sample Collection For subjects aged 9–17 years and 6 months–8 years who have previously received the influenza vaccine, 5 mL of blood will be collected in a tube supplied or recommended by the sponsor on V01 and V03 (D28 [+7 days]), and for subjects aged 6 months–8 years who have not previously received the influenza vaccine, 5 mL of blood will be collected on V01, V03 and V05. Immediately before blood collection, the staff member performing the procedure will confirm who the subject is; verify the subject number assigned to the pre-printed label, including the subject number and sampling stage; and affix the label to the tube. Blood will be collected from the limb opposite to the limb used for vaccination.

[0339] Note: If it is not possible to collect a 5 mL blood sample, a smaller volume may be obtained. .

[0340] 1.7.2 - Sample Manufacturing Following blood collection, the tube should be left standing upright and without shaking for a minimum of 1 hour and a maximum of 24 hours to allow the blood to coagulate. The samples can be stored at room temperature for a maximum of 2 hours; beyond 2 hours, the samples must be refrigerated at a temperature of +2°C to +8°C after the coagulation period at room temperature and centrifuged within a maximum of 24 hours.

[0341] After centrifugation, transfer the serum to an appropriate number of dispensing tubes. These tubes are pre-labeled with adhesive labels identifying the test code, subject number, and sampling stage or visit number. 1.7.3 - Sample Storage and Transportation

[0342] During storage, serum tubes will be kept in a freezer maintained at a temperature of -20°C or below. This temperature will be monitored and documented in an appropriate format throughout the entire testing period. Serum will be transported frozen in packaging containers provided by the carrier, using dry ice to maintain the serum in a frozen state.

[0343] 1.8 - Endpoints and Evaluation Methods 1.8.1 - Safety definition The following definitions are adopted from the ICH E2A guidelines for clinical safety data management: Definitions and criteria for emergency reporting.

[0344] Adverse events (AEs): An AE is any medically undesirable event occurring in a patient or in a clinical study subject who has received a pharmaceutical product, and which is not necessarily causally related to the treatment. Therefore, an AE can be any adverse or unintended sign (including, for example, abnormal laboratory findings), symptom, or disease that is temporarily related to the use of a pharmaceutical product, whether or not it is thought to be related to the pharmaceutical product.

[0345] Therefore, AE can be as follows: • New diseases • Deterioration of the existing condition • Effects of vaccination, including comparison factors • The above combinations

[0346] All AEs include both serious and non-serious AEs.

[0347] Surgical procedures are not AEs; surgical procedures are actions taken to treat a medical condition. An AE is the condition that leads to the taken action (if an AE occurs during the trial period).

[0348] Pre-existing medical conditions should not be reported as adverse events (AEs). However, if a pre-existing medical condition worsens in frequency or intensity after the trial intervention, or if there is a change in clinical significance as reported by the principal investigator, this change should be reported as an AE (exacerbation). This also applies equally to recurrent episodes of pre-existing conditions (e.g., asthma) if their frequency or intensity increases after vaccination.

[0349] Serious adverse events (SAEs): Severe and critical are not synonymous. The term critical is often used to describe the intensity of a particular event, corresponding to Grade 3. This is not the same as critical, based on the outcome or behavioral diagnostic criteria of the subject / event that typically threaten the life or function of the subject. Severity, rather than severity, serves as a guideline for defining regulatory reporting obligations.

[0350] A SAE is the occurrence of any of the following medically undesirable events at any dose. • Leads to death • Life-threatening (The term "life-threatening" refers to an event in which the subject is at risk of death upon occurrence; this term does not refer to an event that is assumed to cause death in more severe cases.) • Hospitalization or extension of existing hospitalization is required (all medical events leading to hospitalization will be recorded and reported as SAEs, except for scheduled hospitalizations or outpatient procedures that did not involve hospitalization prior to enrollment in the study). • To result in a persistent or significant disability / inability ("persistent or significant disability or inability" means that a person's ability to perform normal life functions is substantially impaired). • Congenital abnormalities / birth defects • There is an important medical event (IME).

[0351] Medical and scientific judgment should be made when determining whether an emergency report is appropriate in other situations such as IMEs where there is no immediate threat to life, death, or hospitalization, but there is a risk to the subject's health, or intervention may be required to prevent one of the other outcomes listed in the definition above. These IMEs should also generally be considered serious. Examples of such events include allergic bronchospasm requiring intensive care in an emergency room or at home, a blood disorder or seizure not resulting in hospitalization, or the onset of drug dependence or abuse, or a newly diagnosed diabetes or autoimmune disease.

[0352] Adverse reactions: All adverse and unintended reactions to a pharmaceutical product, regardless of the dosage, should be considered adverse reactions (ARs).

[0353] (The phrase "reaction to a pharmaceutical product" implies that it is reasonable to assume that there is at least a causal relationship between the pharmaceutical product and the adverse event (AE).)

[0354] The following additional definitions are used: Immediate events / responses:

[0355] Immediate events are recorded as medically relevant, spontaneously reported systemic adverse events (AEs), including those related to the administered product, that occur within the first 30 minutes after vaccination.

[0356] Responses from involuntary reporting: Involuntary reporting refers to observed "expected" adverse reactions (signs or symptoms) that are reported under conditions (nature and manifestation) that are listed in advance in the protocol and CRB (e.g., pain or headache at the injection site occurring between D0 and D7 after vaccination).

[0357] Involuntary reports of a response should, by definition, be considered related to the product being administered.

[0358] In the case of injectable vaccines, involuntary reporting of a reaction can be classified as either an involuntary injection-site reaction or an involuntary systemic reaction.

[0359] Voluntary reporting for AE / AR: A spontaneously reported AE is an observed AE that does not meet the conditions pre-listed in the CRB regarding the time frame of diagnosis and / or onset after vaccination. For example, if a headache between D0 and D7 is a spontaneously reported response (i.e., pre-listed in the protocol and CRB), then a headache beginning on D7 is a spontaneously reported response, while a headache beginning on D8 after vaccination is a spontaneously reported AE. Spontaneously reported AEs include both serious (SAEs) and non-serious spontaneously reported AEs.

[0360] Injection site reaction: An injection site reaction (AR) is an inflammatory response (AR) at or around the injection site. Injection site reactions are generally inflammatory reactions. Injection site reactions are considered to be related to the administered product.

[0361] [Table 23]

[0362] Systemic AEs: Systemic AEs are all AEs that are not injection or administration site reactions. Therefore, systemic AEs include headache, fever, and systemic signs such as localized or local signs that are not related to the vaccination or administration site (e.g., erythema that is localized but does not occur at the injection site).

[0363] [Table 24]

[0364] Particularly noteworthy adverse events (AESIs): A particularly noteworthy adverse event is one of the scientific and medical concerns specific to the sponsor's product or program, and continuous monitoring of this concern and prompt reporting by the principal investigator to the sponsor may be appropriate. Such an event warrants further investigation to characterize and understand the concern. Depending on the nature of the event, prompt reporting by the trial sponsor to other third parties (e.g., regulatory authorities) is also warranted.

[0365] 1.8.2 - Security Endpoints The endpoints for safety evaluation are as follows: • The occurrence, nature (PT) duration, intensity, and relationship to vaccination of systemic adverse events (AEs) reported 30 minutes after each vaccine administration, based on voluntary reports. • The occurrence, time to onset, duration, severity, actions taken, and whether the reaction led to early termination of the study, based on involuntary reports (as pre-listed in the subject's record log card and CRB) of injection site and systemic reactions that occurred within up to 7 days after each vaccination. • For each vaccine, for up to 28 days, spontaneously reported adverse events (AEs) were assessed, including their occurrence, nature (MedDRA organ-specific major classification [SOC] and PT), time to onset, duration, severity, relationship to vaccination (for systemic AEs only), and whether the events led to early termination of the study. Throughout the trial, what were the occurrence, characteristics (MedDRA SOC and PT), time to onset, severity diagnostic criteria, relationship with vaccination, outcomes, and events that led to early termination of the trial for SAEs (including AESI)? • The relationship between the occurrence, nature (MedDRA PT), time to onset, and vaccination of AESI throughout the entire study.

[0366] 1.8.3 - Safety assessment method In V01, the principal investigator or their representative will perform a clinically or medically driven physical examination.

[0367] Where applicable, in V03 (D28 [+7 days]) and / or V05, the Principal Investigator or Agent will, if necessary, perform the intended clinical or medically promoted physical examination and question the Subject / Parent / Guardian about any involuntary reported reactions and voluntary reported AEs recorded in the Record Log card, as well as any other AEs that may have occurred since the previous visit.

[0368] 1.8.3.1 - Observation period after immediate vaccination To ensure safety, subjects will be observed for 30 minutes after each vaccine administration. Any adverse events (AEs) that occur during this period will be documented in the source document and recorded in the CRB as follows: • Spontaneous systemic adverse events (AEs) are recorded as immediate AEs in the CRB (indicated as "yes" if present, and details are collected). Involuntary and voluntary injection site reactions, as well as involuntary systemic reactions, are recorded in the CRB in the same manner as any reactions that begin on the day of vaccination. • SAEs are recorded in the CRB and reported to the sponsor in the same manner as any other SAEs.

[0369] 1.8.3.2 - Reactiongenicity (reactions reported involuntarily from day 0 to day 7 after each vaccination) After each vaccination, the subject / parent / guardian will be given a record log card, a digital thermometer, and a flexible ruler, and will be instructed on how to use them. The following items will be recorded by the subject in the record log card on the day of vaccination and for the following seven days (i.e., D0-D7) until resolved: • Daily temperature measurement, including the route of measurement. • Daily measurement or intensity grading of injection site and systemic reactions based on all other involuntary reports. • Actions taken in response to each event (e.g., medication)

[0370] Any involuntary reporting response or any action taken by the subject / parent / guardian to treat and / or manage it will be classified as a CRB using the following list (all applicable items should be reviewed): · none • Medication • Contact from healthcare providers · hospitalization • Suspension of experimental vaccine administration

[0371] The following tables present the injection site reactions and systemic reactions, as pre-listed in the record log card and CRB, along with their intensity scales.

[0372] [Table 25-1] [Table 25-2]

[0373] [Table 26]

[0374] [Table 27-1] [Table 27-2]

[0375] [Table 28]

[0376] [Table 29-1] [Table 29-2]

[0377] Important notes regarding accurate body temperature assessment: Subjects / parents / guardians should measure their body temperature once a day, preferably at the same time each day. The optimal time for measurement is at night, when body temperature is highest. Body temperature should also be measured if there is any obvious fever. The daily body temperature observed and the route of measurement will be recorded on a record log card, and the highest temperature will be recorded by site during CRB. The preferred route for this study is rectal for subjects 6 months to <4 years old, and oral for subjects 4 years and older. However, if the preferred route of measurement cannot be obtained, axillary measurement is also acceptable for subjects 6 months and older. Body temperature before vaccination will also be systematically collected by the principal investigator and recorded in the source document. Tympanometers should not be used.

[0378] 1.8.3.3 - Voluntary Reported Adverse Events In addition to recording involuntary reports of responses, subjects / parents / guardians are instructed to record any other medical events that may occur during the 28-day period following each vaccination. For this purpose, blank spaces are provided on the record log card.

[0379] Information on SAEs will be collected and evaluated throughout the study from enrollment up to six months after the last vaccination. Any SAE occurring at any time during the study will be reported by the principal investigator during the CRB in accordance with the completion instructions provided by the sponsor; this includes checking the “serious” box on the AE CRF and completing the appropriate Death / Safety Supplement CRF. If relevant information is available later (e.g., outcome, medical history, study results, copy of admission report), all information on SAEs will be reported either as part of the initial report or during follow-up reports. If a subject experiences a febrile seizure (fever and seizure related to a neurological event), the evaluation will be in accordance with the “Guidelines for Defining and Collecting Cases of Febrile Seizures,” and this event will be considered an SAE.

[0380] In each case of a spontaneously reported adverse event (AE), regardless of whether it is serious or not, the following information should be recorded: • Start and end dates (all end dates for related AEs are proactively and involuntarily reported. For other events, the principal investigator will provide the end date as it becomes available. AEs for which an end date is not available during the course of the study will be considered ongoing at the end of the study). • Intensity of the event: 1. For measurable spontaneously reported AEs, which are part of the list of involuntary reported reactions, the size of the AE and, in the case of fever, body temperature are collected and analyzed based on the corresponding scale used for involuntary reported reactions. 2. All other spontaneously reported AEs are classified according to the following intensity scale: a. Grade 1: A type of AE that is usually transient and may require minimal treatment or therapeutic intervention. The event generally does not interfere with normal daily activities. b. Grade 2: An AE type that is usually alleviated by additional therapeutic intervention. The event causes discomfort and interferes with normal daily activities, but does not pose a significant or permanent risk of harm to the study participant. c. Grade 3: A type of AE that interrupts normal daily activities, significantly impacts the clinical situation, or may require intensive therapeutic intervention. • Whether the AE is related to the investigational product (in the case of spontaneously reported systemic AEs). The principal investigator will assess the causal relationship between the adverse event (AE) and the investigational product as either "unrelated" or "related." • Actions taken against each AE (e.g., medication) Any action taken by the subject / parent / guardian to treat and / or manage an AE based on any voluntary report is classified as a CRB using the following list (all applicable items should be reviewed): ○ None ○ Medication ○ Contact from healthcare providers ○ Hospitalization ○ Suspension of experimental vaccine administration • Whether the AE is serious For each SAE, the principal investigator will complete all applicable severity criteria (outcome, time elapsed, and relationship to the study procedure). • Whether the examination was terminated due to an adverse event (AE).

[0381] 1.8.3.4 - Adverse events of particular note Throughout the study, AESIs are considered and collected as SAEs. These include new-onset GBS, encephalitis / myelitis (including transverse myelitis), Bell's palsy, seizures, optic neuritis, and brachial neuritis (Sejvar JJ et al. (2011) Vaccine; Vol. 29 (No. 3): pp. 599-612; Bonhoeffer J et al. (2004) Vaccine Vol. 22 (Nos. 5-6): pp. 557-562; Sejvar JJ et al. (2007) Vaccine Vol. 25 (No. 31): pp. 5771-5792).

[0382] 1.8.3.5 - Evaluation of Causal Relationships The principal investigator will assess the causal relationship between each spontaneously reported systemic adverse event (AE) and the administered product, based on the following definitions, as either unrelated or related: • No correlation - The AE is clearly / most likely caused by other etiologies such as the underlying disease, therapeutic intervention, or combination therapy; or the delay between vaccination and the onset of the AE is not consistent with a causal relationship; or the AE began before the first vaccination (screening stage, if applicable). • Relevant - There is a “reasonable possibility” that the AE was caused by the administered product, meaning there is evidence or argument suggesting a causal relationship.

[0383] Note: By convention, all AEs reported at the injection site (whether involuntary or voluntary) and all involuntary systemic AEs are considered to be related to the administered product and are therefore referred to as reactions, without requiring the opinion of the principal investigator regarding the relationship.

[0384] Any adverse events that are likely to be product-related and persist at the end of the trial, regardless of their severity, will be followed up by the principal investigator until they completely disappear or the subject's condition stabilizes. The principal investigator will notify the sponsor of the date and time the event finally disappeared or when "chronicity" was established.

[0385] 1.9 Immunogenicity 1.9.1 Immunogenic endpoints 1.9.1.1 Immunogenicity by HAI method The endpoints for evaluating immunogenicity using the HAI method are as follows: For those aged 9-17 years, and those aged 6 months-8 years who have previously received the influenza vaccine: • Antibody titers of HAI antibody (Ab) obtained on D0 and D28 • Individual HAI antibody titer ratio D28 / D0 • Seroconversion (antibody titer < 10 [1 / dilution {dil}] at D0 and antibody titer ≥ 40 [1 / dil] after injection at D28, or antibody titer ≥ 10 [1 / dil] at D0 and an increase of ≥ 4 times the antibody titer at D28 [1 / dil]). • Percentage of subjects with antibody titers ≥ 40 (1 / dil) in D0 and D28

[0386] For children aged 6 months to 8 years who have not previously received the influenza vaccine: • HAI Ab antibody titers obtained on D0, D28, and D56 • Individual HAI antibody titer ratios D28 / D0 and D56 / D0 • Seroconversion (antibody titer < 10 [1 / dil] at D0, and post-injection antibody titer ≥ 40 [1 / dil] at D28 and D56, or antibody titer ≥ 10 [1 / dil] at D0, and an increase of ≥ 4 times the antibody titer [1 / dil] at D28 and D56). • Percentage of subjects with antibody titers ≥ 40 (1 / dil) in D0, D28, and D56

[0387] 1.9.1.2 Immunogenicity by the virus SN method The endpoints for evaluating immunogenicity using the viral SN method are as follows: For those aged 9-17 years, and those aged 6 months-8 years who have previously received the influenza vaccine: • Individual neutralization test (NT) Ab antibody titers at D0 and D28 • Individual NT Ab antibody titer ratios in D28 (increase ratio in serum after NT vaccination relative to D0) • Subjects with NT Ab antibody titers ≥20 (1 / dil), ≥40 (1 / dil), and ≥80 (1 / dil) on D28. • In D28, the increase ratio of NT Ab antibody titer [post-vaccination / pre-vaccination] was ≥2 and ≥4. • Detectable NT (NT Ab antibody titer ≥ 10 [1 / dil]) at D0 and D28

[0388] For children aged 6 months to 8 years who have not previously received the influenza vaccine: • Individual NT Ab antibody titers at D0, D28, and D56 • Individual NT Ab antibody titer ratios at D28 and D56 (increase ratio in serum after NT vaccination relative to D0) • Subjects with NT Ab antibody titers ≥20 (1 / dil), ≥40 (1 / dil), and ≥80 (1 / dil) on D28 and D56, respectively. • The increase ratio of NT Ab antibody titer [post-vaccination / pre-vaccination] at D28 and D56 was ≥2 and ≥4, respectively. • Detectable NT (NT Ab antibody titer ≥ 10 [1 / dil]) at D0, D28, and D56

[0389] 1.9.2 - Methods for evaluating immunogenicity Titration of anti-influenza virus Ab by inhibition of hemagglutination Test serum samples and quality control serums (sheep, ferox, and / or human serum) are incubated with Sigma type III neuraminidase derived from Vibrio cholerae to remove nonspecific inhibitors. Next, the test serum samples and quality control serums are incubated with erythrocyte (RBC) suspension to induce spontaneous adsorption of anti-aglutinin. Following this, the mixture is centrifuged, and the supernatant containing the treated serum is collected for testing. Ten 2-fold dilutions (starting at 1:10) of the treated test serum samples and quality control serums are incubated with previously titrated influenza antigen at a concentration of 4 hemagglutination units (HAU) / 25 μL. Influenza antigen is not added to serum control wells containing only serum and RBCs. Next, this mixture is incubated, and the RBC suspension is added. After incubation, the results are read. The assay endpoint is the highest serum dilution at which complete inhibition of hemagglutination occurs. Each serum sample is titrated in two independent assays, reporting two values ​​that cannot be distinguished by more than one 2-fold dilution. The GMT between the two values ​​is calculated during statistical analysis. The lower limit of quantification (LLOQ) is set at 1:10, the lowest dilution used in the assay. Antibody titers below this level are reported as <10 (1 / dil). If the lowest / first serum dilution used in this assay shows complete inhibition of hemagglutination, the serum Ab antibody titer is reported as <10 (1 / dil). If the highest / last serum dilution used in this assay shows complete inhibition of hemagglutination, the serum Ab antibody titer is reported as ≥10240 (1 / dil).

[0390] Neutralization test for influenza virus This NT measures antibodies that target the virus-neutralizing epitope of the influenza virus, which may differ from hemagglutination epitopes. Therefore, antibody titers measured by NT may differ from antibody titers measured by HAI.

[0391] To measure NT, serially diluted, heat-inactivated human serum samples are pre-incubated with a fixed amount of challenge virus before adding Maidin-Derby canine kidney (MDCK) cells. After overnight incubation, viral nucleoprotein production in infected MDCK cells is measured by enzyme-linked immunosorbent assay (ELISA) using monoclonal benzoyl

[0392] 1.10 - Determination of statistical methods and sample size 1.10.1 - Statistical methods All statistical analyses are performed under the responsibility of the sponsor's Biostatistics Platform using SAS® software, version 9.4 or later (SAS Institute, Cary, North Carolina, USA). Assumptions and statistical methods regarding the objective

[0393] i.Premise There are no assumptions regarding safety or immunogenicity. All analyses are descriptive.

[0394] ii. Statistical methods For cohorts managed with adjuvant-free QIV-SD, results are described by stage according to the vaccine administered and by age group. Age groups are also pooled within the same vaccine groups as for the primary endpoint. Descriptive results are also shown in two countries by the pooled QIV-HD group (60 μg). Immunogenicity analyses of subgroups based on prior vaccination status and / or baseline serological status are presented where appropriate. If any stage was not completed, analyses for higher doses or the next stage were not performed.

[0395] For cohorts managed with adjuvant-added TIV, the results are described according to the vaccine administered.

[0396] safety Safety endpoints are descriptively analyzed for subjects in the SafAS who received QIV-HD vaccination. Involuntary reports of reactions (involuntary injection site reactions and systemic reactions), voluntary reports of adverse events (AEs), single adverse events (SAEs), and adverse event-associated ailments (AESIs) are summarized. The primary parameters are described as single proportions using the 95% confidence interval (Clopper-Pearson method) (Newcombe RG (1998) Stat Med. Vol. 17: pp. 857-857).

[0397] immunogenicity Immunogenicity endpoints are summarized in 95% confidence intervals (CIs). 95% CIs for GMT and GMT ratio (GMTR) are calculated using a normalized approximation of logarithmically transformed antibody titers. 95% CIs for proportions are based on the Clopper-Pearson method. GMT ratios are obtained between groups using 95% CIs calculated using a normalized approximation of logarithmically transformed antibody titers. Differences in seroconversion rates between groups are calculated with two-sided 95% CIs using the Wilson score method without continuity correction (Newcombe RG (1998), Stat Med. 1998; Vol. 17: pp. 873-890). Additional parameters may be presented where appropriate.

[0398] Inverse cumulative distribution curves are constructed for each strain against baseline (V01) and post-vaccination immunogenicity (D28, or D56, where appropriate).

[0399] The immunogenicity analysis population (IAS) is used for primary immunogenicity analyses.

[0400] 1.10.2 - Population to be analyzed Two main analysis populations are used: the Intensive Analysis Group (IAS) and the Safety Analysis Group (SafAS).

[0401] i. Population for immunogenicity analysis IAS is defined as a subset of randomized subjects who received one dose of the study vaccine (for subjects aged 9–17 years and 6 months–8 years who had previously received the influenza vaccine) or two doses of the same study vaccine (for subjects aged 6 months–8 years who had not previously received the influenza vaccine) and who have post-vaccination blood samples. Subjects are analyzed as treated.

[0402] ii. Population for safety analysis SafAS is defined as individuals who have received at least one dose of the test vaccine (and are therefore scheduled to collect safety data).

[0403] All subjects will undergo a safety analysis as follows: • After administering each dose according to the vaccine actually received by the subject at the dosage considered: • After administering either vaccine according to the first dose administered. If the second dose administered is different, the safety data recorded in V04 and V05 will be excluded from this analysis and listed separately.

[0404] Safety data recorded regarding vaccines administered from the protocol design stage are excluded from this analysis (and listed separately).

[0405] iii. Population used for analysis All random subjects with data in the CRB are taken into account in the description of the population (e.g., predisposition, demographics or baseline characteristics).

[0406] Safety analysis is performed on SafAS.

[0407] Immunogenicity analysis derived from the HAI assay and the SN assay are both performed on IAS.

[0408] 1.10.3 - Handling of missing data and outliers i. Safety No replacement is made. Nevertheless, during statistical analysis, missing relationships are considered relevant. No outlier search is performed. Among all subject lists, partial data and missing data are clearly indicated as missing.

[0409] ii. Immunogenicity To properly manage replicate values for analysis purposes, after managing extreme values as described, the individual geometric mean of all values is calculated for each blood sample. Next, this calculated value is regarded as the antibody titer of that specific blood sample. · When the antibody titer is <LLOQ, use the calculated value LLOQ / 2. · When the antibody titer is ≧LLOQ and <upper limit of quantification (ULOQ) (or ≦ULOQ), use the antibody titer itself. · When the antibody titer is ≧ULOQ (or, >ULOQ), use the calculated value ULOQ.

[0410] Any other substitutions applied to specific endpoints are described in the Statistical Analysis Plan (SAP).

[0411] Missing data are not attributed. No tests or searches for outliers are performed.

[0412] 1.10.4 - Interim / preliminary analysis For stages 1, 2, and 3, we will early, blindly examine 7-day safety data for subjects aged 6 months to 8 years to determine if the following groups are enrolled. Since we are not testing a hypothesis, statistical adjustment is not required.

[0413] Limited statistical analysis of open-label safety and immunogenicity data obtained by D28 or D56 can be performed. Once 6 months of safety data are collected and the database is finalized, the final analysis is conducted.

[0414] Since we are not testing a hypothesis, statistical adjustment is not necessary.

[0415] 1.10.5 - Determining Sample Size and Calculating Power QHD04 is a Phase II trial to describe the safety and immunogenicity of QIV-HD at three different dosages. The sample size is not power-analyzed. The trial includes approximately 700 participants divided into 13 groups, as follows: Groups 1, 2, 3, 5, 9, and 10 each consist of 40 subjects (either previously vaccinated with influenza or not previously vaccinated with influenza) in a 3:1 ratio (QIV-HD:QIV-SD). Group 4 includes 90 subjects (those who have previously received the influenza vaccine or those who have not) in a 1:1 ratio (QIV-HD:QIV-SD). Group 7 includes 60 subjects who have previously received the influenza vaccine in a 1:1 ratio (QIV-HD:QIV-SD). Groups 6 and 8 each consist of 60 subjects who have not previously received the influenza vaccine, in a 1:1 ratio (QIV-HD:QIV-SD or TIV). Groups 11 and 13 each consisted of 60 subjects (either previously vaccinated against influenza or not previously vaccinated against influenza) in a 1:1 ratio (QIV-HD:QIV-SD). Group 12 includes 70 subjects (who have previously received the influenza vaccine or who have not) in a ratio of 3:3:1 (QIV-HD:QIV-HD:QIV-SD). [Examples]

[0416] result 2.1 - Serological Assays 2.1.A - Hemagglutination inhibition test for influenza virus The influenza virus HAI assay is based on the ability of specific anti-influenza antibodies to inhibit the agglutination of RBCs (red blood cell clusters) induced by hemagglutinin (HA) of the influenza virus. The serum to be tested is pre-treated with neuraminidase to remove nonspecific inhibitors and anti-hemagglutinins that may interfere with the test results.

[0417] Influenza virus HA causes agglutination of red cell blockers (RBCs) from various species. Serum from individuals who have been successfully vaccinated against influenza, or from individuals who have previously suffered from the infection, contains high levels of antibodies against these HA antigens. Serial dilutions of serum are incubated with a fixed amount of influenza antigen. When the influenza virus antigen is added to the assay, the antibodies present in the serum sample inhibit RBC agglutination. The assay endpoint is the highest serum dilution at which complete inhibition of hemagglutination occurs.

[0418] Justification / Logical basis Various serological techniques have been developed to evaluate influenza virus vaccine response in clinical trials or for disease detection. These methods include HAI, single-component radiolysis (SRH), viral neutralization (NT), and enzyme-linked immunosorbent assay (ELISA). HAI antibody titers are relevant surrogate markers of protection in vaccinated populations; therefore, influenza virus HAI assays are a suitable serological method due to their strain specificity and ease of implementation.

[0419] 2.1.B - Influenza virus neutralization test The influenza virus neurotransmitter (NT), sometimes also identified as the serum neutralization assay, is an in vitro functional assay that measures the level of influenza virus neutralizing antibodies in human serum. The NT is based on the ability of neutralizing antibodies against influenza virus to inhibit infection of Maidin-Derby canine kidney (MDCK) cells with the influenza virus. Serum, diluted 2-fold, is pre-incubated with 50 μL of 100 tissue culture infectious doses (TCID) / 50 μL of influenza virus before the addition of MDCK cells. After overnight incubation, the cells are fixed, and the presence of influenza virus nucleoprotein (NP) in infected cells is detected by ELISA. Absence of infectivity constitutes a positive neutralization reaction, indicating the presence of influenza virus-specific neutralizing antibodies in human serum.

[0420] Justification / Logical basis NT is a highly sensitive and specific assay that detects neutralizing antibodies against influenza viruses (Rowe T et al. (1999) J Clin Microbiol. 37 (No. 4): pp. 937-943) and virus-specific antibodies against all types of influenza viruses. NT can detect antibodies in human serum at levels that would not be detectable using HAI assays (ibid.). For some influenza virus strains, NT assays have been shown to yield higher antibody titers than HAI assays (Hancock K et al. (2009) N Engl J Med. 361 (No. 20): pp. 1945-952).

[0421] 2.2 - Target Factors The results presented in Example 2 of this specification are specific results from the study outlined in Example 1, which included 665 randomized subjects from 13 sites in the United States and 3 sites in Canada. A total of 661 subjects (99.4%) received the vaccine and were included in the Safety Analysis (SafAS) population. Table 20A lists the number of doses actually administered for each study design. A total of 645 subjects (97%) completed the study per protocol. A total of 642 subjects (96.5%) who had post-vaccination blood samples were included in the Immunogenicity Analysis (IAS) population. Since the results are being analyzed in progress, only safety data from the Canadian treatment group in this study are reported herein.

[0422] [Table 30]

[0423] Table 20B shows baseline demographics between vaccine groups based on the immunogenicity analysis population. In the United States, considering the all-age group (6 months to under 18 years), each QIV-HD dose was primarily compared to its QIV-SD control cohort from relevant trial groups as per the trial design (following a randomization schedule) to ensure similar distributions of age and stage in the comparison, and also individually compared to the pooled QIV-SD group (i.e., all subjects who received QIV-SD, regardless of trial stage). The overall distributions of each demographic (sex, age, and racial origin) were similar, indicating relatively balanced features across vaccine groups.

[0424] [Table 31-1] [Table 31-2] [Table 31-3]

[0425] 2.3 - Safety results Executive summary of safety results: A. US cohort Participants: Of the 639 randomized US participants, 635 received vaccination, all of whom were randomized (122 received QIV-HD 30μg, 121 received QIV-HD 45μg, 158 received QIV-HD 60μg, and 234 received QIV-SD) (Figure 4). In the QIV-SD group, 228 participants completed the trial. Five participants in the QIV-HD 30μg group, one participant in the QIV-HD 45μg group, and six participants in the QIV-HD 60μg group did not complete their follow-up visit 28 days after vaccination.

[0426] The majority of participants were white and non-Hispanic. The overall distribution of each demographic (sex, age, and racial origin) was relatively similar across vaccine groups (Table 1C).

[0427] Safety and involuntary reporting responses: The rate of spontaneously reported AEs was similar regardless of antigen dose (Table 20D). This was also observed when limited to participants 6 months to <3 years old (Table 20F). No related SAEs, AEs leading to study discontinuation, or deaths were reported. Two SAEs occurred within 28 days of vaccination in participants who received QIV-HD 60 μg, which were thought to be unrelated to the study vaccine: a febrile seizure 22 days after initial vaccine administration in a 16-month-old participant (which may be considered a particularly noteworthy AE); and a respiratory multinuclear virus infection 12 days after initial vaccine administration in a 2-year-old participant. No other AESIs occurred in this study. One immediate (<30-minute) spontaneously reported AE thought to be related to the study vaccine: a mild exacerbation of chronic pain in the right shoulder was reported in a 14-year-old participant who received QIV-HD 60 μg.

[0428] Reactionogenicity (involuntary injection site reactions and involuntary systemic reactions) was slightly higher in the QIV-HD group than in the QIV-SD group (Table 20D). The most frequent injection site reactions were tenderness at the injection site (in participants 6 months to <3 years old) and pain at the injection site (in participants 3 years to <18 years old) (Figures 6A-6D). In participants 6 months to <3 years old, the most frequent systemic reactions were abnormal crying, drowsiness, loss of appetite, and irritability. In participants 3 years to <5 years old and 5 years to <9 years old, the most frequent systemic reactions included discomfort and muscle pain. In participants 9 years to <18 years old, the most frequent systemic reactions included headache and muscle pain (Figure 6D).

[0429] Most involuntary reports of adverse events were Grade 1 or Grade 2 (Figures 11A–11B and 12A–12B). The proportion of involuntary reports of injection site reactions of Grade 3 tended to increase with increasing vaccine dose (Table 20D). There was no other evidence of adverse events associated with higher doses. See also Figures 16A–16B and 17A–17B.

[0430] B. Canadian cohort: Participants: All participants received vaccination as randomized: 13 received QIV-HD 60 μg, and 13 received adjuvant-added TIV (7.5 μg HA / strain). All participants completed the study. Demographic data for the Canadian cohort are shown in Table 1D.

[0431] Safety and involuntary reporting responses: Summary data on spontaneously reported adverse events (AEs) in the Canadian cohort is shown in Table 20E. One participant experienced a severe otitis media (SAE) during the 6-month safety follow-up period after the last dose of the vaccine. This SAE was assessed by the principal investigator as unrelated to the study vaccine. The proportion of individual injection site reactions and involuntary systemic reactions is shown by vaccine and grade in Figures 15A–15B.

[0432] Detailed safety results: 2.3.1 - Overview of safety findings for subjects aged 6 months to 17 years Table 20C outlines the overall safety findings for all age groups in this study: immediate AE information (within 30 minutes post-vaccination), involuntary injection site and systemic reactions (up to 7 days post-vaccination), voluntary AE / AR and AE / AR leading to withdrawal from the study (up to 28 days post-vaccination), and SAEs (overall study), including AESI.

[0433] [Table 32-1] [Table 32-2] [Table 32-3] [Table 32-4] [Table 32-5]

[0434] [Table 33]

[0435] [Table 34]

[0436] [Table 35]

[0437] Safety data related to children aged 6 months to under 18 years is summarized in the following section.

[0438] Safety analyses were conducted on the SafAS, defined as subjects who received at least one dose of the test vaccine. The SafAS consisted of a total of 661 subjects (635 in the United States and 26 in Canada).

[0439] 2.3.2 - Target population aged 9 to under 18 years (Groups 12 and 13 [Stage 1] - United States) Involuntary reporting responses between D0 and D7 The proportion of subjects reporting at least one involuntary response within 7 days of vaccination was similar among the three QIV-HD groups (30 μg, 45 μg, and 60 μg) and slightly higher in each QIV-HD group compared to the QIV-SD group: 82.8% (24 / 29), 80.0% (24 / 30), 80.0% (24 / 30), and 65.9% (27 / 41), respectively (Table 21).

[0440] Involuntary injection site reactions: The proportion of subjects who reported at least one involuntary injection site reaction was 79.3% (23 / 29) in the QIV-HD group (30 μg, 45 μg, and 60 μg), 79.3% (23 / 29), 76.7% (23 / 30), and 61.0% (25 / 41) in the QIV-SD group, respectively (Table 21).

[0441] Systemic reactions reported involuntarily: The proportion of subjects reporting at least one involuntary systemic reaction was 51.7% (15 / 29) in the QIV-HD (30 μg, 45 μg, and 60 μg) group, 70.0% (21 / 30) in the QIV-SD group, 63.3% (19 / 30) in the QIV-SD group, and 39.0% (16 / 41) in the QIV-SD group, respectively (Table 21).

[0442] Non-serious adverse events (AEs) reported spontaneously between days D0 and D28, and SAEs / AESI throughout the entire study. Within 30 minutes of vaccination, one subject in the QIV-HD (60 μg) group experienced one spontaneously reported adverse event (AE), which is also considered to be an aggravating reaction (AR) (Table 21).

[0443] Within 28 days of vaccination, the proportion of subjects experiencing at least one spontaneously reported non-serious adverse event (AE) in the QIV-HD (30 μg, 45 μg, and 60 μg) and QIV-SD groups was 20.7% (6 / 29), 26.7% (8 / 30), 13.3% (4 / 30), and 16.7% (7 / 42), respectively. The proportion of subjects experiencing at least one spontaneously reported non-serious adverse reaction (AR) in the QIV-HD (30 μg, 45 μg, and 60 μg) and QIV-SD groups was 3.4% (1 / 29), 6.7% (2 / 30), 10.0% (3 / 30), and 4.8% (2 / 42), respectively (Table 21).

[0444] [Table 36-1] [Table 36-2]

[0445] The SOC with the highest incidence of non-serious AEs reported spontaneously was "gastrointestinal disorders." In the QIV-HD (30 μg) group, 3 AEs were reported by 10.3% (3 / 29) of subjects; in the QIV-HD (45 μg) group, 3 AEs were reported by 7.6% (2 / 30) of subjects; in the QIV-HD (60 μg) group, 3 AEs were reported by 6.7% (2 / 30) of subjects; and in the QIV-SD group, 4 AEs were reported by 7.1% (3 / 42) of subjects. In the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups, the most frequently reported PT was nausea.

[0446] Throughout the study, no subjects experienced any adverse events (AEs), serious adverse events (SAEs), fatal SAEs, or AESIs that led to the discontinuation of the study (Table 21).

[0447] 2.3.3 - Target population aged 5-8 years (Group 9 [Stage 1], Group 10 [Stage 2], and Group 11 [Stage 3] - United States) Involuntary reporting responses between D0 and D7 The proportion of subjects who reported at least one involuntary response within 7 days of receiving any of the vaccines was similar among the QIV-HD groups (30 μg, 45 μg, and 60 μg) and slightly higher in each QIV-HD group compared to the QIV-SD group: 87.5% (28 / 32), 90.3% (28 / 31), 86.7% (26 / 30), and 73.5% (36 / 49), respectively (Table 22).

[0448] Involuntary injection site reactions: The proportion of subjects who reported at least one involuntary injection site reaction was 78.1% (25 / 32) in the QIV-HD group (30 μg, 45 μg, 60 μg), 87.1% (27 / 31), 86.7% (26 / 30), and 71.4% (35 / 49) in the QIV-SD group, respectively (Table 22).

[0449] There were very few reports of Grade 3 reactions. The incidence of involuntary injection site reactions after the second vaccination did not improve compared to the first vaccination.

[0450] Systemic reactions reported involuntarily: The proportion of subjects reporting at least one involuntary systemic reaction was 50.0% (16 / 32) in the QIV-HD (30 μg, 45 μg, 60 μg) group, 38.7% (12 / 31) in the QIV-SD group, 50.0% (15 / 30) in the QIV-SD group, and 40.8% (20 / 49) in the QIV-SD group, respectively (Table 22).

[0451] There were very few reports of Grade 3 reactions. The incidence of involuntary systemic reactions after the second vaccination did not improve compared to the first vaccination.

[0452] Non-serious adverse events (AEs) reported spontaneously between days D0 and D28, and SAEs / AESI throughout the entire study. No subjects experienced any spontaneously reported adverse events (AEs) or adverse reactions (ARs) within 30 minutes of receiving any type of vaccine.

[0453] Within 28 days of receiving any of the vaccines, the proportion of subjects in the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups who experienced at least one spontaneously reported non-serious adverse event (AE) was 37.5% (12 / 32), 35.5% (11 / 31), 26.7% (8 / 30), and 28.6% (14 / 49), respectively. The proportion of subjects in the QIV-HD (30 μg, 45 μg, and 60 μg) and QIV-SD groups who experienced at least one spontaneously reported non-serious adverse event (AR) was 3.1% (1 / 32), 3.2% (1 / 31), 3.3% (1 / 30), and 2.0% (1 / 49), respectively (Table 22).

[0454] [Table 37-1] [Table 37-2]

[0455] The SOC with the highest incidence of spontaneously reported non-serious AEs was "respiratory, thoracic, and mediastinal disorders." In the QIV-HD (30 μg) group, 7 AEs were reported by 15.6% (5 / 32) of subjects; in the QIV-HD (45 μg) group, 12 AEs were reported by 25.8% (8 / 31) of subjects; in the QIV-HD (60 μg) group, 3 AEs were reported by 10.0% (3 / 30) of subjects; and in the QIV-SD group, 10 AEs were reported by 12.2% (6 / 49) of subjects. The most frequently reported PT in the QIV-HD (30 μg, 45 μg, and 60 μg) groups and the QIV-SD group was cough.

[0456] Throughout the study, no subjects experienced any adverse events (AEs), serious adverse events (SAEs), lethal SAEs, or AESIs that led to the discontinuation of the study (Table 22).

[0457] 2.3.4 - Target population aged 36 months to under 5 years (Group 1 [Stage 1], Group 2 [Stage 2], and Group 4 [Stage 3] - United States) Involuntary reporting responses between D0 and D7 The proportion of subjects who reported at least one involuntary response within 7 days of receiving either vaccine was similar between the two QIV-HD groups (30 μg and 45 μg) and slightly lower in the QIV-HD (60 μg) and QIV-SD groups: 71.9% (23 / 32) for the QIV-HD (30 μg, 45 μg, and 60 μg) groups and 72.4% (21 / 29) for the QIV-SD group, 56.8% (25 / 44) for the QIV-HD groups, and 60.3% (41 / 68) for the QIV-SD group (Table 23).

[0458] Involuntary injection site reactions: The proportion of subjects who reported at least one involuntary injection site reaction was 71.9% (23 / 32) in the QIV-HD group (30 μg, 45 μg, and 60 μg), 69.0% (20 / 29), 54.5% (24 / 44), and 52.9% (36 / 68) in the QIV-SD group, respectively (Table 23).

[0459] There were very few reports of Grade 3 reactions after the first vaccination. The incidence of involuntary injection site reactions after the second vaccination did not improve compared to the first vaccination. There were no reports of Grade 3 reactions after the second vaccination.

[0460] Systemic reactions reported involuntarily: The proportion of subjects reporting at least one involuntary systemic reaction was 40.6% (13 / 32) in the QIV-HD (30 μg, 45 μg, 60 μg) group, 44.8% (13 / 29) in the QIV-SD group, 29.5% (13 / 44) in the QIV-SD group, and 35.3% (24 / 68) in the QIV-SD group, respectively (Table 23).

[0461] There were very few reports of Grade 3 reactions after the first vaccination. The incidence of involuntary systemic reactions after the second vaccination did not improve compared to the first vaccination. There were no reports of Grade 3 reactions after the second vaccination.

[0462] Non-serious adverse events (AEs) reported spontaneously between days D0 and D28, and SAEs / AESI throughout the entire study. No subjects experienced any spontaneously reported adverse events (AEs) or adverse reactions (ARs) within 30 minutes of receiving any type of vaccine.

[0463] Within 28 days of vaccination, the proportion of subjects in the QIV-HD (30 μg, 45 μg, and 60 μg) and QIV-SD groups who experienced at least one spontaneously reported non-serious adverse event (AE) was 37.5% (12 / 32), 46.7% (14 / 30), 40.9% (18 / 44), and 30.9% (21 / 68), respectively. The proportion of subjects in the QIV-HD (30 μg, 45 μg, and 60 μg) and QIV-SD groups who experienced at least one spontaneously reported non-serious adverse event (AR) was 0% (0 / 32), 3.3% (1 / 30), 2.3% (1 / 44), and 2.9% (2 / 68), respectively (Table 23).

[0464] The SOC with the highest incidence of spontaneously reported non-serious AEs was "respiratory, thoracic, and mediastinal disorders." In the QIV-HD (30 μg) group, 6 AEs were reported by 15.6% (5 / 32) of subjects; in the QIV-HD (45 μg) group, 8 AEs were reported by 23.3% (7 / 30) of subjects; in the QIV-HD (60 μg) group, 15 AEs were reported by 20.5% (9 / 44) of subjects; and in the QIV-SD group, 19 AEs were reported by 23.5% (16 / 68) of subjects. The most frequently reported PT in the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups was cough.

[0465] Throughout the study, no subjects experienced any adverse events (AEs), serious adverse events (SAEs), lethal SAEs, or AESIs that led to the discontinuation of the study (Table 23).

[0466] [Table 38-1] [Table 38-2]

[0467] 2.3.5 - Subjects aged 6 to under 36 months (Group 3 [Stage 2], Group 5 [Stage 3], and Group 6-7 [Stage 4] - United States) Involuntary reporting responses between D0 and D7 The proportion of subjects who reported at least one involuntary response within 7 days of receiving any of the vaccines was similar among the three QIV-HD groups (30 μg, 45 μg, and 60 μg), and slightly higher in each QIV-HD group compared to the QIV-SD group: 69.0% (20 / 29) for the QIV-HD (30 μg, 45 μg, and 60 μg) groups, 70.0% (21 / 30) for the QIV-SD group, 66.7% (36 / 54) for the QIV-HD group, and 56.8% (42 / 74) for the QIV-SD group, respectively (Table 24).

[0468] Involuntary injection site reactions: The proportion of subjects who reported at least one involuntary injection site reaction was 62.1% (18 / 29) in the QIV-HD group (30 μg, 45 μg, 60 μg), 63.3% (19 / 30), 51.9% (28 / 54), and 43.2% (32 / 74) in the QIV-SD group, respectively (Table 24).

[0469] Following vaccination 1, the most frequently reported involuntary injection site reactions in the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups were tenderness, followed by erythema. Less frequently reported injection site reactions in each group included swelling, sclerosis, and contusion.

[0470] Following vaccination 2, the most frequently reported involuntary injection site reaction was tenderness. Swelling, erythema, sclerosis, and bruising were reported less frequently. The frequency of injection site reactions reported by subjects in the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups did not increase after vaccination 2.

[0471] The majority of involuntary injection site reactions in the four vaccine groups were of grade 1 severity.

[0472] There were few reports of grade 3 tenderness, swelling, and induration after vaccination 1. Grade 3 erythema and contusions were not reported in any vaccine group.

[0473] Following vaccination 2, there were no reports of Grade 3 involuntary injection site reactions in the three QIV-HD groups, and only one subject in the QIV-SD group experienced Grade 3 severe injection site tenderness.

[0474] Systemic reactions reported involuntarily: The proportion of subjects who experienced at least one involuntary systemic reaction within 7 days of receiving any of the vaccines was similar across all study groups for each type of involuntary systemic reaction. The overall proportions for the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group were 62.1% (18 / 29), 53.3% (16 / 30), 44.4% (24 / 54), and 50.0% (37 / 74), respectively.

[0475] Following vaccination 1, the most frequently reported involuntary systemic reactions in the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups were hypersensitivity, followed by drowsiness, abnormal crying, and loss of appetite. Systemic reactions that were less frequently reported by subjects in the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups were fever and vomiting.

[0476] Following vaccination 2, the most frequently reported involuntary systemic reactions in the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group were hypersensitivity, followed by drowsiness and abnormal crying. Systemic reactions that were not reported as frequently by subjects in the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group were loss of appetite, fever, and vomiting.

[0477] The majority of systemic reactions reported spontaneously in the four vaccine groups were of grade 1 or grade 2 severity.

[0478] Following vaccination 1, there were very few reports of grade 3 reactions in the four vaccine groups. Following vaccination 2, one subject each reported grade 3 drowsiness and grade 3 loss of appetite in the QIV-HD (45 μg) group, and one subject reported grade 3 fever in the QIV-HD (60 μg) group. Furthermore, the incidence of involuntary systemic reactions after vaccination 2 did not improve compared to vaccination 1.

[0479] Non-serious adverse events (AEs) reported spontaneously between days D0 and D28, and SAEs / AESI throughout the entire study. No subjects experienced any spontaneously reported adverse events (AEs) or adverse reactions (ARs) within 30 minutes of receiving any type of vaccine.

[0480] Within 28 days of vaccination, the proportion of subjects in the QIV-HD (30μg, 45μg, 60μg) and QIV-SD groups who experienced at least one spontaneously reported non-serious systemic adverse event (AE) was 55.2% (16 / 29), 43.3% (13 / 30), 40.7% (22 / 54), and 50.7% (38 / 75), respectively. The proportion of subjects in the QIV-HD (30μg, 45μg, 60μg) and QIV-SD groups who experienced at least one spontaneously reported non-serious adverse reaction (AR) was 6.9% (2 / 29), 13.3% (4 / 30), 5.6% (3 / 54), and 6.7% (5 / 75), respectively. One subject in the QIV-HD (45μg) group experienced spontaneously reported AR at the injection site (Table 24).

[0481] [Table 39-1] [Table 39-2]

[0482] The SOC with the highest incidence of spontaneously reported non-serious AEs was "respiratory, thoracic, and mediastinal disorders," with 8 AEs reported by 17.2% (5 / 29) of subjects in the QIV-HD (30 μg) group; 17 AEs reported by 30% (9 / 30) of subjects in the QIV-HD (45 μg) group; 10 AEs reported by 7.4% (4 / 54) of subjects in the QIV-HD (60 μg) group; and 20 AEs reported by 18.7% (14 / 75) of subjects in the QIV-SD group. The most frequently reported PT in this SOC for the QIV-HD (30 μg, 45 μg, and 60 μg) and QIV-SD groups was cough.

[0483] None of the subjects experienced any adverse events (AEs) or fatal SAEs that led to the discontinuation of the study (Table 24).

[0484] In the QIV-HD (60 μg) group, two cases of SAE (febrile seizure, thought to be an AESI) and RSV infection were reported between days D0 and D28. Both SAEs were considered unrelated to the vaccine by the principal investigator and the sponsor.

[0485] A 16-month-old subject in group 6 (who had not been previously vaccinated against influenza) who received two doses of the experimental vaccine experienced a febrile seizure (SAE). For 22 days after vaccination, the subject had a fever of 104°F (axillary), and a sibling witnessed a possible seizure at home. The subject's seizure episode reportedly included rolling of the eyes, lethargy, shivering, and foaming at the mouth for approximately 3 minutes. The subject did not lose consciousness. The mother brought the subject to the emergency room, where out-of-hospital records reported nasal congestion and a possible upper respiratory tract infection. However, the mother ruled out any other symptoms. The subject was not hospitalized and did not experience any further seizure episodes or the onset of any new symptoms. The mother felt the fever was due to the subject's teething. The subject received a second dose of the experimental vaccine after this febrile seizure episode because the mother did not report the subject's seizure episode until visit 04 after the administration of the second dose of the experimental vaccine. Prior to enrollment in this study, the subjects had last received hepatitis A, MMR, PCV13, and varicella vaccines approximately one month before the first dose of the influenza vaccine in this study. The principal investigator received hospital records reporting upper respiratory tract infections and believed the febrile episodes were not related to the study vaccine.

[0486] A group of six 2-year-old subjects (who had not previously received an influenza vaccine) who received two doses of the study vaccine developed a SAE (Severe Acute Embolism) due to RSV infection. Symptoms of cough and dyspnea began 12 days after the first dose, and a fever of up to 103°F was recorded 14 days after the first dose. The RSV test was positive, and the influenza test was negative. As the subject's condition worsened, the subject went to the emergency room and was hospitalized for 16 days after the first dose. The subject was also diagnosed with otitis media and was treated with amoxicillin during hospitalization. The symptoms resolved 22 days after the first dose. The principal investigator considered the RSV infection unrelated to the study vaccine, given that there was an RSV outbreak in the area during that period and that the subject likely contracted RSV through disease contact.

[0487] 2.3.6 - Targeting children aged 6 to under 24 months (Group 8 [Stage 4] - Canada) Involuntary reporting responses between D0 and D7 Within 7 days of receiving either vaccine, all subjects (100%) receiving QIV-HD (60 μg) and adjuvant-added TIV reported at least one involuntary response (Table 20C).

[0488] Involuntary injection site reactions: In both the QIV-HD (60 μg) group and the adjuvant-added TIV group, the proportion of subjects who reported at least one involuntary injection site reaction was 69.2% (9 / 13) (Table 20C).

[0489] In the QIV-HD (60 μg) and TIV adjuvant-containing vaccine groups, the majority of involuntary injection site reactions were of grade 1 severity.

[0490] Following vaccination 1, there were no reports of Grade 3 involuntary injection site reactions in either the QIV-HD (60 μg) group or the adjuvant-added TIV group.

[0491] Following vaccination 2, one patient in the QIV-HD (60 μg) group experienced a grade 3 erythema.

[0492] Systemic reactions reported involuntarily: All subjects (100%) receiving QIV-HD (60 μg) and adjuvant-added TIV reported at least one involuntary systemic reaction (Table 20C).

[0493] In the QIV-HD (60 μg) and TIV adjuvant-added vaccine groups, the majority of involuntary injection site reactions were of grade 1 or grade 2 severity.

[0494] Following vaccination 1, there were no reports of Grade 3 involuntary systemic reactions in either the QIV-HD (60 μg) group or the adjuvant-enhanced TIV group.

[0495] Following vaccination 2, one patient in the QIV-HD (60 μg) group experienced grade 3 abnormal crying, and one patient in the adjuvant-added TIV group experienced grade 3 fever.

[0496] Non-serious AEs and SAEs reported spontaneously between D0 and D28, as well as SAE / AESI throughout the entire study. No subjects experienced any spontaneously reported adverse events (AEs) or adverse reactions (ARs) within 30 minutes of receiving any type of vaccine.

[0497] Within 28 days of vaccination, the proportion of subjects in the QIV-HD (60 μg) and adjuvant-added TIV groups who experienced at least one spontaneously reported non-serious systemic adverse event (AE) was 84.6% (11 / 13) and 92.3% (12 / 13), respectively. The proportion of subjects in the QIV-HD (60 μg) and adjuvant-added TIV groups who experienced at least one spontaneously reported non-serious systemic adverse reaction (AR) was 7.7% (1 / 13) and 15.4% (2 / 13), respectively. One subject in the adjuvant-added TIV group experienced a spontaneously reported non-serious injection-site AR (Table 20C).

[0498] The SOC with the highest incidence of non-serious AEs reported spontaneously was "infection and invasiveness." In the QIV-HD (60 μg) group, 25 AEs were reported by 76.9% (10 / 13) of subjects, while in the adjuvant-added TIV group, 21 AEs were reported by 69.2% (9 / 13) of subjects. The most frequently reported PT in both the QIV-HD (60 μg) group and the adjuvant-added TIV group was nasopharyngitis.

[0499] None of the subjects experienced any adverse events (AEs), serious adverse events (SAEs), lethal SAEs, or AESIs that would lead to the discontinuation of the study.

[0500] 2.3.7 - Overall Safety Conclusions Vaccination with 30, 45, and 60 μg doses of the QIV-HD formulation was found to be safe and well-tolerated in children 6 months to under 18 years of age, and no safety concerns were identified. In general, QIV-HD showed slightly higher reactiongenicity (involuntary injection site reactions and involuntary systemic reactions) compared with QIV-SD. However, reactiongenicity did not increase with increasing QIV-HD dose (i.e., HA content). Furthermore, in subjects who received two doses of the test vaccine at intervals of approximately 28 days, reactiongenicity after administration of the second dose did not increase compared to reactiongenicity after administration of the first dose.

[0501] In both QIV-HD and QIV-SD, the rates of spontaneously reported events, AEs, SAEs, fatal SAEs, and AESIs leading to trial discontinuation were similar within 28 days of either vaccination. Throughout the trial, no deaths or related SAEs were reported in either group. Two SAEs (both in the QIV-HD 60 μg dose group, a febrile seizure [considered to be an AESI] and an RVS infection) were evaluated by the investigator and sponsor and reported as unrelated. Between D29 and the end of the trial, one SAE (severe bilateral otitis in the adjuvant-added TIV group) was evaluated by the investigator and sponsor and reported as unrelated.

[0502] The safety profiles of QIV-HD and adjuvant-added TIV were similar in the Canadian cohort of this study.

[0503] 2.4 - Immunogenicity results GMT 28 days after vaccination improved with increasing age (Figures 7A-7E and Table 25). GMT generally improved with increasing QIV-HD dose, particularly in children aged 6 months to <3 years. This difference was not evident in children aged 3 to <5 years. Analysis adjusted for pre-vaccination antibody titers also showed the same trend.

[0504] In participants aged 6 months to <3 years who had not previously received vaccination (who received two doses of QIV-HD 60 μg), the GMT was higher after the second vaccine dose than after the first vaccine dose (Figures 13A-13B). However, the GMT was lower after the second vaccine dose in unvaccinated participants than after the single dose in previously vaccinated participants.

[0505] For H1N1 and H3N2, in participants who had not previously received vaccination, the GMT observed after a single dose of QIV-HD was similar to that observed after two doses of QIV-SD, while B antibody levels were lower.

[0506] Overall, the ratio of GMT of QIV-HD to QIV-SD was higher with QIV-HD 60 μg than with QIV-HD 30 μg or QIV-HD 45 μg (Figures 8A-8E). For QIV-HD 60 μg, the ratio of GMT to QIV-SD (95% CI) was 1.35 (0.94, 1.94) for A / H1N1, 2.51 (1.77, 3.55) for A / H3N2, 1.60 (1.17, 2.18) for B / Victoria, and 1.51 (1.13, 2.03) for B / Yamagata. For participants aged 6 months to <3 years, the GMT ratio (95% CI) to QIV-SD was highest for A / H1N1 (4.24, 2.05, 8.76), A / H3N2 (3.14, 1.53, 6.44), B / Victoria (2.04, 1.10, 3.77), and B / Yamagata (1.92, 1.08, 3.41).

[0507] The geometric mean ratio of post-vaccination versus pre-vaccination antibody titers is shown in Figures 14A–14E. In particular, the geometric mean of the post-vaccination / pre-vaccination antibody titer ratio tended to be higher for QIV-HD 60 μg compared to other QIV-HD doses in participants aged 6 months to <3 years. Overall seroconversion rates were generally highest with QIV-HD 60 μg, but the differences between QIV-HD doses were small (Figures 9A–9E). Seroconversion rates were generally higher in younger participants (6 months to <3 years and 3 to <5 years) than in older participants (5 to <9 years and 9 to <18 years).

[0508] Overall, the ratio of serum neutralizing antibody GMT over 28 days after the last vaccine dose to day 0 was highest with QIV-HD 60 μg (Figures 10A-10E). For QIV-HD 60 μg, the serum neutralizing antibody GMT ratio (95% CI) was 29.1 (19.6, 43.2) for A / H1N1, 5.5 (4.6, 6.7) for A / H3N2, 19.9 (15.1, 26.3) for B / Victoria, and 14.1 (11.1, 17.8) for B / Yamagata. Overall, in participants aged 6 months to <3 years, the GMT ratio (95% CI) of serum neutralizing antibodies was highest for A / H1N1: 19.8 (11.2, 35.1) for IIV4 SD, 79.9 (31.1, 205.3) for IIV4-HD 30 μg, 164.8 (73.8, 367.9) for IIV4-HD 45 μg, and 169.6 (84.6, 339.7) for IIV4-HD 60 μg. See also Figure 18.

[0509] [Table 40]

[0510] detail: Immunogenicity data from the study in Example 1, involving children aged 6 months to under 18 years, are presented.

[0511] Immunogenicity analysis was performed on IAS, defined as a subset of randomized subjects who received either one dose of the study vaccine (for subjects 9–18 years of age and for subjects 6 months–8 years of age who had previously received the influenza vaccine) or two doses of the same study vaccine (for subjects 6 months–8 years of age who had not previously received the influenza vaccine) and who had post-vaccination blood samples. Subjects were analyzed as treated.

[0512] 2.4.1 - Target population aged 9 to under 18 years (Groups 12 and 13 [Stage 1] - United States) HAI GMT At baseline (before vaccination), GMT was similar between the QIV-HD (30 μg, 45 μg, and 60 μg) and QIV-SD groups for A / H1N1, A / H3N2, and B / Victoria strains. For the B / Yamagata strain, GMT was similar between the QIV-HD (30 μg and 60 μg) and QIV-SD groups, with a tendency to be lower in the QIV-HD (45 μg) group (Table 26A).

[0513] GMT improved 28 days after vaccination compared to baseline (Table 26).

[0514] HAI GMT (Comparison of QIV-HD with QIV-SD) The GMT ratios of QIV-HD (30 μg, 45 μg, 60 μg) to the QIV-SD group were 0.98, 1.02, and 1.28, respectively, for the A / H1N1 strain; 1.38, 1.86, and 1.54, respectively, for the A / H3N2 strain; 1.21, 1.23, and 1.43, respectively, for the B / Victoria strain; and 1.16, 0.99, and 1.15, respectively, for the B / Yamagata strain (Table 26B).

[0515] HAI GMTR (Geometric mean of individual antibody titer ratios after / before vaccination) 28 days after vaccination, the GMTRs for the QIV-HD (30μg, 45μg, 60μg) group and the QIV-SD group were 5.20, 6.45, 6.20, and 5.07 for A / H1N1 strains, respectively; 3.05, 4.30, 3.56, and 1.67 for A / H3N2 strains, respectively; 7.63, 8.00, 6.57, and 5.07 for B / Victoria strains, respectively; and 5.52, 10.7, 4.90, and 4.39 for B / Yamagata strains, respectively (Figure 26A). Compared to the QIV-SD group, the GMTR of QIV-HD (30 μg, 45 μg, and 60 μg) was similar for A / H1N1, higher for A / H3N2 and B / Victoria strains, and either similar or higher for B / Yamagata strain.

[0516] HAI Cell Conversion Rate 28 days after vaccination, the seroconversion rates for the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group were 51.7%, 55.2%, 56.7%, and 56.1% for the A / H1N1 strain, respectively; 28.6%, 41.4%, 43.3%, and 14.6% for the A / H3N2 strain, respectively; 62.1%, 75.9%, 63.3%, and 53.7% for the B / Victoria strain, respectively; and 62.1%, 69.0%, 55.2%, and 41.5% for the B / Yamagata strain, respectively (Figure 27). In general, the seroconversion rates of QIV-HD (30 μg, 45 μg, and 60 μg) compared to QIV-SD were higher for A / H3N2, B / Victoria, and B / Yamagata strains, and similar for A / H1N1 strain.

[0517] SN GMT (baseline and post-vaccination) At baseline (before vaccination), GMT was generally similar among the QIV-HD (30 μg, 45 μg, and 60 μg) groups compared to the QIV-SD group for all four influenza strains (Table 28).

[0518] Twenty-eight days after vaccination, all GMTs were significantly improved compared to baseline (Table 28). Compared to QIV-SD, the QIV-HD (60 μg) group had higher GMTs for A / H3N2 and B / Victoria strains, and similar GMTs for A / H1N1 and B / Yamagata strains.

[0519] SN GMTR (Geometric mean of individual antibody titer ratios before / after vaccination) The GMTRs for the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group are shown in Table 28. Compared to the QIV-SD group, the QIV-HD (60 μg) group had a higher GMTR for A / H3N2 and B / Victoria strains, while having a similar GMTR for A / H1N1 and B / Yamagata strains.

[0520] SN: Subjects with a four-fold increase in antibody titer. Table 28 shows the number of subjects with a fourfold increase in antibody titer 28 days after vaccination in the QIV-HD (30 μg, 45 μg, and 60 μg) group and the QIV-SD group. The number of subjects with a fourfold increase in antibody titer compared to QIV-SD in the QIV-HD (60 μg) group was similar for A / H1N1, B / Victoria, and B / Yamagata strains, but was higher for the A / H3N2 strain.

[0521] [Table 41-1] [Table 41-2]

[0522] [Table 42]

[0523] [Table 43]

[0524] [Table 44-1] [Table 44-2] [Table 44-3]

[0525] 2.4.2 - Target population aged 5-8 years (Group 9 [Stage 1], Group 10 [Stage 2], and Group 11 [Stage 3] - United States) HAI GMT (baseline and after last vaccination) At baseline (before vaccination), GMT was similar between the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups for A / H1N1, A / H3N2, B / Victoria, and B / Yamagata strains (Table 29).

[0526] Finally, 28 days after vaccination, all GMT levels were significantly improved compared to baseline (Table 30).

[0527] HAI GMT (Comparison of QIV-HD / QIV-SD) The GMT ratios of QIV-HD (30 μg, 45 μg, and 60 μg) to the QIV-SD group were 0.61, 0.69, and 0.88 for the A / H1N1 strain; 2.09, 2.60, and 2.99 for the A / H3N2 strain; 1.01, 1.38, and 1.89 for the B / Victoria strain; and 1.06, 1.15, and 1.52 for the B / Yamagata strain (Table 30).

[0528] HAI GMTR (Geometric mean of individual antibody titer ratios after / before vaccination) 28 days after the last vaccination, the GMTRs for the QIV-HD (30μg, 45μg, 60μg) group and the QIV-SD group were 4.10, 4.65, 6.51, and 7.58, respectively, for A / H1N1; 3.95, 7.64, 6.55, and 3.90, respectively, for A / H3N2 strains; 8.00, 9.96, 11.9, and 11.1, respectively, for B / Victoria strains; and 5.86, 7.05, 11.0, and 6.42, respectively, for B / Yamagata strains (Table 29). Compared to the QIV-SD group, the GMTRs of QIV-HD (30μg, 45μg, and 60μg) were similar to or higher for A / H3N2, B / Victoria, and B / Yamagata strains, but lower for A / H1N1 strains.

[0529] HAI seroconversion rate (after last vaccination) 28 days after the last vaccination, the seroconversion rates for the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group were 48.3%, 40.0%, 66.7%, and 64.4% for A / H1N1, respectively; 44.8%, 66.7%, 69.2%, and 51.2% for A / H3N2 strains; 79.3%, 86.7%, 88.9%, and 77.8% for B / Victoria strains; and 44.8%, 66.7%, 88.9%, and 79.5% for B / Yamagata strains, respectively. The seroconversion rates for the QIV-HD (60 μg) group against the four influenza strains were higher or similar to those of the QIV-HD (30 μg and 45 μg) and QIV-SD groups (Table 31).

[0530] SN GMT (baseline and after last vaccination) At baseline (before vaccination), GMT was similar among the QIV-HD (30 μg, 45 μg, 60 μg) groups compared to the QIV-SD group for all four influenza strains (Table 32).

[0531] Lastly, 28 days after vaccination, all GMTs were significantly improved compared to baseline. Compared to the QIV-SD group, the QIV-HD (60 μg) group had higher GMTs for A / H3N2 and B / Victoria strains, and similar GMTs for A / H1N1 and B / Yamagata strains (Table 32).

[0532] SN GMTR (Geometric mean of individual antibody titer ratios before / after vaccination) The GMTRs for the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group are shown in Table 32. Compared to the QIV-SD group, the QIV-HD (60 μg) group had a higher GMTR for the A / H3N2 strain, while having similar GMTRs for the A / H1N1, B / Victoria, and B / Yamagata strains.

[0533] SN: Subjects with a four-fold increase in antibody titer. Table 32 shows the number of subjects who showed a fourfold increase in antibody titer 28 days after the last vaccination in the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group. The number of subjects who showed a fourfold increase in antibody titer compared to QIV-SD in the QIV-HD (60 μg) group was similar for the A / H1N1, B / Victoria, and B / Yamagata strains, and higher for the A / H3N2 strain.

[0534] [Table 45-1] [Table 45-2]

[0535] [Table 46]

[0536] [Table 47]

[0537] [Table 48-1] [Table 48-2] [Table 48-3]

[0538] 2.4.3 - Target population aged 36 months to under 5 years (Group 1 [Stage 1], Group 2 [Stage 2], and Group 4 [Stage 3] - United States) HAI GMT (baseline and post-vaccination) At baseline (before vaccination), GMT was similar between the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups for A / H1N1, A / H3N2, B / Victoria, and B / Yamagata strains (Table 33).

[0539] Lastly, 28 days after vaccination, all GMT levels showed a significant improvement compared to baseline (Table 34).

[0540] HAI GMT (Comparison of QIV-HD with QIV-SD) The GMT ratios of QIV-HD (30 μg, 45 μg, 60 μg) to the QIV-SD group were 0.54, 0.57, and 0.50, respectively, for the A / H1N1 strain; 1.56, 2.97, and 2.37, respectively, for the A / H3N2 strain; 0.80, 0.84, and 1.05, respectively, for the B / Victoria strain; and 0.96, 0.91, and 1.27, respectively, for the B / Yamagata strain (Table 34).

[0541] HAI GMTR (Geometric mean of individual antibody titer ratios after / before vaccination) 28 days after the last vaccination, the GMTRs for the QIV-HD (30μg, 45μg, 60μg) group and the QIV-SD group were 10.2, 11.2, 20.1, and 20.8 for A / H1N1 strains, respectively; 8.41, 14.3, 12.3, and 4.58 for A / H3N2 strains, respectively; 14.0, 13.5, 18.5, and 12.9 for B / Victoria strains, respectively; and 11.7, 11.5, 20.3, and 9.83 for B / Yamagata strains, respectively (Table 33). Compared to the QIV-SD group, the GMTRs for QIV-HD (30μg, 45μg, and 60μg) were higher for A / H3N2, B / Victoria, and B / Yamagata strains, and lower for A / H1N1 strains.

[0542] HAI seroconversion rate (after last vaccination) 28 days after the last vaccination, the seroconversion rates for the QIV-HD (30μg, 45μg, 60μg) group and the QIV-SD group were 75.0%, 77.8%, 86.8%, and 84.6% for the A / H1N1 strain, respectively; 71.4%, 88.9%, 81.6%, and 50.0% for the A / H3N2 strain, respectively; 85.7%, 92.6%, 84.2%, and 89.2% for the B / Victoria strain, respectively; and 85.7%, 92.0%, 92.3%, and 89.1% for the B / Yamagata strain, respectively. The seroconversion rates in the QIV-HD (30 μg, 45 μg, 60 μg) groups were higher for A / H3N2 compared to QIV-SD, and similar for A / H1N1, B / Victoria, and B / Yamagata strains (Table 35).

[0543] SN GMT (baseline and after last vaccination) At baseline (before vaccination), GMT was similar between the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups for A / H3N2, B / Victoria, and B / Yamagata strains. For the A / H1N1 strain, GMT was similar between the QIV-HD (45 μg and 60 μg) and QIV-SD groups, with QIV-HD (30 μg) tending to have a higher GMT (Table 36).

[0544] All GMTs were significantly improved compared to baseline 28 days after the last vaccination. Compared to the QIV-SD group, the QIV-HD (60 μg) group had lower GMTs for A / H1N1 strains, higher GMTs for A / H3N2 and B / Yamagata strains, and similar GMTs for B / Victoria strains (Table 36).

[0545] SN GMTR (Geometric mean of individual antibody titer ratios before / after vaccination) The GMTRs for the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group are shown in Table 36. Compared to the QIV-SD group, the QIV-HD (60 μg) group had a higher GMTR for A / H3N2, B / Victoria, and B / Yamagata strains, and a similar GMTR for A / H1N1 strain (Table 36).

[0546] SN: Subjects with a four-fold increase in antibody titer. Table 36 shows the number of subjects who showed a fourfold increase in antibody titer 28 days after the last vaccination in the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group. The number of subjects who showed a fourfold increase in antibody titer compared to QIV-SD in the QIV-HD (60 μg) group was similar for the A / H1N1, B / Victoria, and B / Yamagata strains, and higher for the A / H3N2 strain.

[0547] [Table 49-1] [Table 49-2] [Table 49-3]

[0548] [Table 50]

[0549] [Table 51]

[0550] [Table 52-1] [Table 52-2] [Table 52-3]

[0551] 2.4.4 - Subjects aged 6 to under 36 months (Group 3 [Stage 2], Group 5 [Stage 3], and Groups 6 and 7 [Stage 4] - United States) HAI GMT At baseline (before vaccination), GMT was similar between the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups for A / H1N1, B / Victoria, and B / Yamagata strains. For A / H3N2, GMT was similar between the QIV-HD (45 μg and 60 μg) and QIV-SD groups, with a tendency to be lower in the QIV-HD (30 μg) group (Table 37).

[0552] 28 days after the last vaccination, all GMTs were significantly improved compared to baseline. The GMTs for the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group were 303, 248, 603, and 142 for A / H1N1, respectively; 149, 239, 505, and 161 for A / H3N2 strains, respectively; 167, 186, 276, and 135 for B / Victoria strains, respectively; and 320, 343, 556, and 290 for B / Yamagata strains, respectively (Table 37). The GMTs for the QIV-HD (30 μg, 45 μg, 60 μg) group were higher than those for the QIV-SD group, with QIV-HD (60 μg) having the highest GMT for all influenza strains.

[0553] HAI GMTR (Geometric mean of individual antibody titer ratios after / before vaccination) 28 days after the last vaccination, the GMTRs for the QIV-HD (30μg, 45μg, 60μg) group and the QIV-SD group were 30.6, 35.1, 44.2, and 9.41, respectively, for A / H1N1; 20.2, 18.6, 22.8, and 9.72, respectively, for A / H3N2 strains; 16.5, 18.6, 34.2, and 15.4, respectively, for B / Victoria strains; and 23.0, 21.7, 50.3, and 21.1, respectively, for B / Yamagata strains. The GMTR for all four influenza strains in the QIV-HD (60μg) group was higher compared to the QIV-HD (30μg, 45μg) group and the QIV-SD group. In the A / H1N1 and A / H3N2 strains, GMTR levels were higher in the QIV-HD (30 μg, 45 μg) group compared to the QIV-SD group, and similar levels were observed in the B / Victoria and B / Yamagata strains (Table 37).

[0554] HAI GMT (Comparison of QIV-HD with QIV-SD) The GMT ratios for the QIV-HD (30 μg, 45 μg, 60 μg) and QIV-SD groups were 2.13, 1.75, and 4.24, respectively, for A / H1N1 strains; 0.93, 1.49, and 3.14, respectively, for A / H3N2 strains; 1.23, 1.38, and 2.04, respectively, for B / Victoria strains; and 1.10, 1.18, and 1.92, respectively, for B / Yamagata strains (Table 38). The GMT ratios between the QIV-HD (60 μg) and QIV-SD groups were higher for all four influenza strains compared to the GMT ratios of the QIV-HD (30 μg and 45 μg) groups.

[0555] HAI GMT (comparison of QIV-SD to QIV-HD) in previously unvaccinated subjects The GMT ratio between post-administration 1 in the QIV-HD (30 μg, 45 μg, 60 μg) groups and post-administration 2 in the QIV-SD group was considerably smaller than the GMT ratio between post-administration 2 of QIV-HD (30 μg, 45 μg, 60 μg) and post-administration 2 of QIV-SD. For post-administration 1 in the three QIV-HD groups, the range was 0.15 to 0.90 compared to post-administration 2 of QIV-SD; for post-administration 2 in the QIV-HD (30 μg) group, the range was 0.93 to 2.42 compared to post-administration 2 of QIV-SD; for post-administration 2 in the QIV-HD (45 μg) group, the range was 1.81 to 3.29 compared to post-administration 2 of QIV-SD; and for post-administration 2 in the QIV-HD (60 μg) group, the range was 1.87 to 4.47 compared to post-administration 2 of QIV-SD (Table 39). The QIV-HD (60 μg) group had a higher GMT ratio compared to QIV-HD (30 μg), and QIV-HD (60 μg) had a higher GMT ratio compared to QIV-HD (45 μg), excluding the B / Yamagata strain (Table 39).

[0556] Despite the small number of previously vaccinated subjects, a similar trend was observed in the QIV-HD (60 μg) group, showing a higher GMT ratio (Table 40).

[0557] HAI Cell Conversion Rate 28 days after the last vaccination, the seroconversion rates for the QIV-HD (30μg, 45μg, 60μg) group and the QIV-SD group were 91.7%, 84.6%, 84.8%, and 56.1% for the A / H1N1 strain, respectively; 91.7%, 92.0%, 87.0%, and 71.2% for the A / H3N2 strain, respectively; 79.2%, 84.0%, 91.3%, and 75.8% for the B / Victoria strain, respectively; and 100.0%, 88.0%, 95.7%, and 92.4% for the B / Yamagata strain, respectively.

[0558] The seroconversion rates of QIV-HD (30μg, 45μg, 60μg) were higher than those of QIV-SD for all four vaccine strains, with the exception of the B / Yamagata strain in the case of QIV-HD (45μg). The differences in seroconversion rates between QIV-HD (30μg, 45μg, 60μg) and QIV-SD ranged from 28.55 to 35.61 for the A / H1N1 strain, 15.74 to 20.79 for the A / H3N2 strain, 3.41 to 15.55 for the B / Victoria strain, and -4.42 to 7.58 for the B / Yamagata strain (Table 41).

[0559] In subjects who had not been previously vaccinated, the seroconversion rate at 1 post-administration in the QIV-HD (30 μg, 45 μg, 60 μg) groups was considerably lower than the seroconversion rate at 2 post-administration in the QIV-SD group and at 2 post-administration in the QIV-HD (30 μg, 45 μg, 60 μg) groups. The seroconversion rates at 1 post-administration in the three QIV-HD groups ranged from 23.1% to 66.7%; at 2 post-administration in the QIV-SD group ranged from 47.8% to 93.5%; and at 2 post-administration in all three QIV-HD groups ranged from 76.9% to 100.0% (Tables 42 and 43).

[0560] SN GMT (baseline and after last vaccination) At baseline (before vaccination), GMT was similar among QIV-HD (30 μg, 45 μg, 60 μg) compared to QIV-SD for all four influenza strains (Table 44).

[0561] 28 days after the last vaccination, all GMTs were significantly improved compared to baseline. The GMTs for the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group were 2700, 2000, 4535, and 663 for A / H1N1 strains, respectively; 237, 360, 623, and 271 for A / H3N2 strains, respectively; 208, 237, 332, and 126 for B / Victoria strains, respectively; and 354, 480, 660, and 340 for B / Yamagata strains, respectively (Table 44). The GMTs for the QIV-HD (30 μg, 45 μg, 60 μg) group were higher than those for the QIV-SD group for all four influenza strains, and QIV-HD (60 μg) induced a higher SN GMT (Table 44).

[0562] SN GMTR (Geometric mean of individual antibody titer ratios before / after vaccination) GMTRs for the QIV-HD (30 μg, 45 μg, 60 μg) group and the QIV-SD group were 79.9, 165, 170, and 19.8 for A / H1N1 strain, respectively; 5.56, 5.85, 7.13, and 4.04 for A / H3N2 strain, respectively; 20.2, 22.4, 35.8, and 14.5 for B / Victoria strain, respectively; and 14.6, 18.0, 22.7, and 11.6 for B / Yamagata strain, respectively (Table 44). GMTRs in the QIV-HD (30 μg, 45 μg, 60 μg) group tended to increase with increasing dose and were higher compared to the QIV-SD group (Table 44).

[0563] Targets with a 4x increase in SN 28 days after the last vaccination, the number of subjects with a fourfold increase in antibody titer in the QIV-HD (30μg, 45μg, 60μg) group and the QIV-SD group was 19 / 26 (95.0%), 23 / 27 (100%), 41 / 54 (95.3%), and 46 / 71 (76.7%) for the A / H1N1 strain, respectively; and 13 / 26 (65.0%) and 13 / 27 (5%) for the A / H3N2 strain, respectively. The percentages were 9.1%, 27 / 54 (65.9%), and 30 / 71 (50.8%), respectively for the B / Victoria strain; 18 / 26 (90.0%), 19 / 27 (82.6%), 40 / 54 (93.0%), and 45 / 71 (76.3%), respectively for the B / Yamagata strain; 17 / 26 (89.5%), 22 / 27 (95.7%), 39 / 54 (90.7%), and 44 / 71 (74.6%), respectively (Table 44). The number of subjects with a fourfold increase was similar across all four influenza strains among the three QIV-HD (30 μg, 45 μg, 60 μg) groups, and higher compared to the QIV-SD group (Table 44).

[0564] As shown in Figure 5, two doses of QIV-HD (60 μg) administered at a one-month interval resulted in a higher GMT than a single dose of QIV-HD. Furthermore, QIV-HD (60 μg) resulted in a significantly higher GMT after the second dose compared to after the second dose of QIV-SD. These data suggest that two doses of QIV-HD (60 μg) may be particularly beneficial in subjects that have not been previously vaccinated (e.g., subjects aged 6 to under 36 months).

[0565] [Table 53-1] [Table 53-2]

[0566] [Table 54]

[0567] [Table 55]

[0568] [Table 56]

[0569] [Table 57]

[0570] [Table 58]

[0571] [Table 59-1] [Table 59-2]

[0572] [Table 60-1] [Table 60-2] [Table 60-3]

[0573] 2.4.5 - Overall Conclusions on Immunogenicity executive summary: This study demonstrated that QIV-HD, containing 60 μg HA / strain, improved immunogenicity in children and adolescents without negatively impacting the benefit-risk balance of the vaccine. As expected, overall reactogenicity was greater with QIV-HD than with QIV-SD. The greatest effect on immunogenicity occurred in the youngest children (6 months to 3 years). Immunogenicity remained high even after the second vaccination, confirming that QIV-HD improves the immune response when administered in two doses in children who have not previously received the vaccine.

[0574] This study demonstrated that, particularly in the youngest children, an antigen dose of 60 μg improved immunogenicity against all four influenza strains. Despite a total antigen dose of 240 μg, safety and reactiongenicity appeared to be similar to that of QIV-SD, even in the youngest children.

[0575] detail: In US subjects aged 6 months to under 18 years who received QIV-HD 30 μg or QIV-HD 45 μg, the GMT ratio for A / H3N2 was slightly higher compared to subjects who received QIV-SD. On the other hand, the QIV-HD 60 μg group tended to have higher GMT ratios for all strains. This trend was most pronounced in subjects aged 6 to under 36 months who received QIV-HD 60 μg (Table 38), in which case the GMT ratio for each strain ranged from 1.92 to 4.24 compared to QIV-SD. The GMTR (geometric mean of individual antibody titer ratios after / before vaccination) for both HAI and SN assays also showed a similar trend, with subjects aged 6 to under 36 months who received the QIV-HD 60 μg dose formulation exhibiting the highest immune response. The seroconversion rates in the QIV-HD 30μg, 45μg, and 60μg groups were still higher than those in the QIV-SD group, but there was no clear trend of increasing seroconversion rates with increasing QIV-HD dosage. However, seroconversion rates are more variable and are not considered to provide as much information as GMT for dose selection decisions. Ultimately, hemagglutination inhibitor (HAI) antibody titers can be used as a correlate of protection for inactivated influenza vaccines in children. In particular, Black et al. described a 1:629 cutoff for HAI antibody titers as a predictor for a 90% protection rate (Black et al. (2011) Pediatr Infect Dis J vol. 30 (no. 12): pp. 1081-1085). As shown in Table 45, the QIV-HD 60μg group tended to have a larger number of subjects with HAI antibody titers ≥1:629.

[0576] [Table 61] [Examples]

[0577] Safety of QIV-HD in children aged 6 to 35 months 3.1. General Test Design To evaluate the safety of QIV-HD, a US safety sentinel cohort of 100 participants was enrolled in an uncontrolled, open-label design that did not include comparator vaccines.

[0578] Vaccination Regarding the sentinel cohort for safety, eligible subjects who received QIV-HD vaccination were as follows: • Participants who had previously received an influenza vaccine received one dose of QIV-HD on day 0 (D), without a comparator vaccine. Subjects who had not previously received an influenza vaccine received two doses of QIV-HD without a comparator vaccine. Each dose was administered 28 days apart (D0 and D28).

[0579] Note: Subjects who have not been previously vaccinated are defined as those who have not received at least two doses of seasonal influenza vaccine during the previous influenza season. These subjects received two doses of the study vaccine at least 28 days apart after enrollment in the study. Subjects who have previously received only one dose of any influenza vaccine, or whose vaccination history is unknown, are also considered to have not been previously vaccinated at the time of enrollment and will receive two doses of the study vaccine at least 28 days apart. Subjects who have been previously vaccinated are defined as those who have received at least two doses of seasonal influenza vaccine during the previous influenza season. These subjects received only one dose of the study vaccine after enrollment in this study.

[0580] Collection of safety data All subjects were observed for 30 minutes after vaccination, and any voluntary, spontaneously reported systemic adverse events (AEs) that occurred during that time were recorded as immediate, voluntary, systemic AEs.

[0581] In all subjects, involuntary responses were collected up to 7 days after each vaccination, and voluntary adverse events (AEs) were collected up to 28 days after each vaccination.

[0582] 3.2.Results Tables 46 and 47 present the predispositions and demographic summaries of sentinel subjects.

[0583] [Table 62]

[0584] [Table 63]

[0585] Tables 48A, 48B, and 48C present a summary of safety after each of the following vaccinations, Vaccination 1 and Vaccination 2, respectively: immediate AE information (within 30 minutes post-vaccination), involuntary injection site and systemic reactions (up to 7 days post-vaccination), voluntary AE / AR and AE leading to study discontinuation (up to 28 days post-vaccination), and SAEs, including AESI (overall study). n is the number of subjects who experienced the endpoint listed in the first column. M is the number of subjects for which data is available regarding the relevant endpoint. Percentages are based on M.

[0586] [Table 64]

[0587] [Table 65]

[0588] [Table 66]

[0589] Table 49 presents a summary of vaccine-related SAEs and Grade 3 fevers after vaccination.

[0590] [Table 67]

[0591] Tables 50A, 50B, and 50C present summaries of involuntary reports within 7 days following either vaccination, vaccination 1, and vaccination 2, respectively. n is the number of subjects who experienced the endpoint listed in the first column. M is the number of subjects for whom data is available regarding the relevant endpoint. Percentages are based on M.

[0592] [Table 68]

[0593] [Table 69]

[0594] [Table 70]

[0595] Tables 51A, 51B, and 51C summarize voluntary reported adverse events (AEs) and adverse reactions (ARs) within 28 days after either vaccination, vaccination 1, and vaccination 2, respectively. n is the number of subjects who experienced the endpoint listed in the first column. n AE is the number of adverse events.

[0596] [Table 71]

[0597] [Table 72]

[0598] [Table 73]

[0599] Table 52 summarizes spontaneously reported adverse events (AEs) and adverse reactions (ARs) within 28 days of vaccination in sentinel subjects by age group. n is the number of subjects who experienced the endpoint listed in the first column. M is the number of subjects for which data is available regarding the relevant endpoint. Percentages are based on M. n AE is the number of AEs.

[0600] [Table 74]

[0601] Table 53 summarizes spontaneously reported adverse events (AEs) and adverse reactions (ARs) within 28 days of vaccination in sentinel subjects for each previous influenza vaccination. n is the number of subjects who experienced the endpoint listed in the first column. M is the number of subjects for which data is available regarding the relevant endpoint. Percentages are based on M. n AE is the number of AEs.

[0602] [Table 75]

Claims

1. A pharmaceutical composition comprising a QIV-HD vaccine for use in a method of immunizing children against influenza viruses, wherein the QIV-HD vaccine is a quadrivalent influenza vaccine containing 30 μg to 60 μg of HA from each of four influenza virus strains, the four strains being one Victoria lineage influenza B strain, one Yamagata lineage influenza B strain, one H1N1 influenza A strain, and one H3N2 influenza A strain, and the method comprising the step of administering the QIV-HD vaccine to a child between 6 months and under 18 years of age.

2. A pharmaceutical composition comprising a QIV-HD vaccine for use in a method of immunizing children against the influenza virus, wherein the method applies to children: a. 30 μg, 45 μg, or 60 μg of hemagglutinin from H1N1 influenza A virus strain per dose; b. 30 μg, 45 μg, or 60 μg of hemagglutinin from H3N2 influenza A virus strain per dose; c. 30 μg, 45 μg, or 60 μg of hemagglutinin from Yamagata lineage influenza B virus strains per dose; d. 30 μg, 45 μg, or 60 μg of hemagglutinin from Victoria lineage influenza B virus strains per dose. The process includes administering a QIV-HD vaccine containing; A pharmaceutical composition intended for children aged 6 months to under 18 years.

3. A pharmaceutical composition according to claim 1 or 2, which prevents influenza virus infection in children.

4. A pharmaceutical composition according to claim 1 or 2, which induces a protective immune response in children.

5. The pharmaceutical composition according to claim 4, wherein the immune response is an antibody response.

6. The vaccine contains hemagglutinin from the H1N1 influenza A virus strain per dose. The pharmaceutical composition according to claim 1 or 2, comprising: 30 μg of hemagglutinin from H3N2 influenza A virus strain per dose; 30 μg of hemagglutinin from Yamagata lineage influenza B virus strain per dose; and 30 μg of hemagglutinin from Victoria lineage influenza B virus strain per dose.

7. The pharmaceutical composition according to claim 1 or 2, wherein the vaccine comprises, per dose, 45 μg of hemagglutinin from an H1N1 influenza A virus strain; per dose, 45 μg of hemagglutinin from an H3N2 influenza A virus strain; per dose, 45 μg of hemagglutinin from a Yamagata lineage influenza B virus strain; and per dose, 45 μg of hemagglutinin from a Victoria lineage influenza B virus strain.

8. The pharmaceutical composition according to claim 1 or 2, wherein the vaccine comprises, per dose, 60 μg of hemagglutinin from an H1N1 influenza A virus strain; per dose, 60 μg of hemagglutinin from an H3N2 influenza A virus strain; per dose, 60 μg of hemagglutinin from a Yamagata lineage influenza B virus strain; and per dose, 60 μg of hemagglutinin from a Victoria lineage influenza B virus strain.

9. A pharmaceutical composition comprising a QIV-HD vaccine for use in a method of immunizing children against the influenza virus, wherein the method is for children aged 6 months to under 18 years: a. 60 μg of hemagglutinin from H1N1 influenza A virus strain per dose; b. 60 μg of hemagglutinin from the H3N2 influenza B virus strain per dose; c. 60 μg of hemagglutinin from the Yamagata lineage influenza B virus strain per dose; d. 60 μg of hemagglutinin from Victoria lineage influenza B virus strain per dose. A pharmaceutical composition comprising the step of administering a QIV-HD vaccine containing [a specific substance].

10. The pharmaceutical composition according to any one of claims 1 to 9, wherein the vaccine is administered intramuscularly.

11. For children, a. Between 6 months and under 36 months of age; b. Ages 3 to under 5; c. Ages 5 to under 9; and / or d. Ages 9 to under 18 The pharmaceutical composition according to any one of claims 1 to 10.

12. The pharmaceutical composition according to any one of claims 1 to 11, wherein the target child is between 6 months and under 24 months of age.

13. The pharmaceutical composition according to any one of claims 1 to 12, wherein the vaccine is administered once or twice to the same subject.

14. The pharmaceutical composition according to claim 13, wherein the dose is administered in a volume of 0.70 mL.

15. The pharmaceutical composition according to any one of claims 1 to 14, wherein the vaccine is administered using a pre-filled syringe.

16. The pharmaceutical composition according to any one of claims 1 to 15 is for children who have not previously received an influenza vaccine.

17. The pharmaceutical composition according to claim 16, wherein the subject who has not been previously vaccinated is between 6 months and under 9 years of age, and is provided with two doses of the vaccine.

18. The pharmaceutical composition according to claim 17, wherein the two doses of the vaccine are provided 28 days apart.

19. The subject is a pharmaceutical composition according to any one of claims 1 to 15, for a person who has previously received an influenza vaccine.

20. The pharmaceutical composition according to claim 19, wherein the subject is administered a single dose of vaccine.

21. The pharmaceutical composition according to any one of claims 1 to 20, which, when administered, reduces the incidence of acute otitis media (AOM), acute lower respiratory tract infection (ALRI, e.g., pneumonia), hospitalization, and / or drug use.

22. The pharmaceutical composition according to any one of claims 1 to 21, wherein two doses of the vaccine are administered to subjects who have not been vaccinated against influenza, and the administration of two doses of the vaccine results in a higher geometric mean titer (GMT) for each of the strains used for vaccination compared to vaccination using QIV-SD, the QIV-SD being a quadrivalent influenza vaccine containing 15 μg or less of HA for each of four influenza virus strains, the four strains being one Victoria lineage influenza B strain, one Yamagata lineage influenza B strain, one H1N1 influenza A strain, and one H3N2 influenza A strain.

23. The pharmaceutical composition according to any one of claims 1 to 22, wherein the administration of the vaccine results in a higher serum neutralized geometric mean titer (GMT) for each of the strains used for vaccination compared to vaccination using QIV-SD, and the QIV-SD is a quadrivalent influenza vaccine containing 15 μg or less of HA for each of four influenza virus strains, the four strains being one Victoria lineage influenza B strain, one Yamagata lineage influenza B strain, one H1N1 influenza A strain, and one H3N2 influenza A strain.

24. The administration produced a geometric mean HI antibody titer (GMT) ratio (QIV-HD / QIV-SD) higher than the GMT ratio of TIV-HD / TIV-SD in adults aged 65 years or older. QIV-SD is a quadrivalent influenza vaccine containing 15 μg or less of HA from each of four influenza virus strains, the four strains being one Victoria lineage influenza B strain, one Yamagata lineage influenza B strain, one H1N1 influenza A strain, and one H3N2 influenza A strain. TIV-HD is a trivalent influenza vaccine containing more than 15 μg of HA from each of three influenza virus strains, the three strains being one H1N1 influenza A strain, one H3N2 influenza A strain, and one Victoria lineage influenza B strain or Yamagata lineage influenza B strain. The TIV-SD is a trivalent influenza vaccine containing 15 μg or less of HA from each of three influenza virus strains, wherein the three strains are one H1N1 influenza A strain, one H3N2 influenza A strain, and one Victoria lineage influenza B strain or Yamagata lineage influenza B strain, according to any one of claims 1 to 23.

25. The pharmaceutical composition according to any one of claims 22 to 24, for children aged 6 months to under 3 years.

26. The pharmaceutical composition according to any one of claims 1 to 25, wherein the vaccine is inactivated or attenuated.

27. The pharmaceutical composition according to claim 26, wherein the vaccine is inactivated.

28. The pharmaceutical composition according to claim 26, wherein the vaccine is attenuated.

29. The pharmaceutical composition according to any one of claims 1 to 28, wherein the vaccine is a split virus vaccine.

30. The pharmaceutical composition according to any one of claims 1 to 29, wherein the vaccine contains an adjuvant.

31. The pharmaceutical composition according to any one of claims 1 to 29, wherein the vaccine does not contain an adjuvant.

32. The pharmaceutical composition according to any one of claims 1 to 31, wherein the target population is immunocompromised children.

33. A pharmaceutical composition according to any one of claims 1 to 32, which is high-risk for use in children.

34. The pharmaceutical composition according to any one of claims 1 to 33, for children who have or have had asthma, diabetes, heart disease, HIV, AIDS, or cancer.

35. The pharmaceutical composition according to any one of claims 1 to 34, wherein the vaccine is safe and well-tolerated in children.

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