Next-generation influenza vaccines: opportunities and challenges

Abstract

Seasonal influenza vaccines lack efficacy against drifted or pandemic influenza strains. Developing improved vaccines that elicit broader immunity remains a public health priority. Immune responses to current vaccines focus on the haemagglutinin head domain, whereas next-generation vaccines target less variable virus structures, including the haemagglutinin stem. Strategies employed to improve vaccine efficacy involve using structure-based design and nanoparticle display to optimize the antigenicity and immunogenicity of target antigens; increasing the antigen dose; using novel adjuvants; stimulating cellular immunity; and targeting other viral proteins, including neuraminidase, matrix protein 2 or nucleoprotein. Improved understanding of influenza antigen structure and immunobiology is advancing novel vaccine candidates into human trials.

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Fig. 1: A spectrum of efficacy for influenza vaccines.
Fig. 2: Structural basis for the induction of broadly neutralizing antibodies against HA.
Fig. 3: Structural basis for the induction of neutralizing antibodies against NA.

References

  1. 1.

    Osterholm, M. T., Kelley, N. S., Sommer, A. & Belongia, E. A. Efficacy and effectiveness of influenza vaccines: a systematic review and meta-analysis. Lancet Infect. Dis. 12, 36–44 (2012).

  2. 2.

    Lewnard, J. A. & Cobey, S. Immune history and influenza vaccine effectiveness. Vaccines 6, 28 (2018).

  3. 3.

    Centers for Disease Control and Prevention. Seasonal influenza vaccine effectiveness, 2004–2018 https://www.cdc.gov/flu/vaccines-work/past-seasons-estimates (CDC, 2019).

  4. 4.

    Erbelding, E. J. et al. A universal influenza vaccine: the strategic plan for the national institute of allergy and infectious diseases. J. Infect. Dis. 218, 347–354 (2018). This article lays out a strategic plan for the development of a universal influenza vaccine and reiterates the commitment from the US government for further investment in influenza vaccine research.

  5. 5.

    Nabel, G. J. & Fauci, A. S. Induction of unnatural immunity: prospects for a broadly protective universal influenza vaccine. Nat. Med. 16, 1389–1391 (2010). This article discusses novel approaches for the development of next-generation vaccines that can elicit a safe and effective immune response against evolving influenza virus strains.

  6. 6.

    Paules, C. I. & Fauci, A. S. Influenza vaccines: good, but we can do better. J. Infect. Dis. 219, S1–S4 (2019).

  7. 7.

    Paules, C. I., Marston, H. D., Eisinger, R. W., Baltimore, D. & Fauci, A. S. The pathway to a universal influenza vaccine. Immunity 47, 599–603 (2017).

  8. 8.

    Paules, C. I., McDermott, A. B. & Fauci, A. S. Immunity to influenza: catching a moving target to improve vaccine design. J. Immunol. 202, 327–331 (2019).

  9. 9.

    Barbey-Martin, C. et al. An antibody that prevents the hemagglutinin low pH fusogenic transition. Virology 294, 70–74 (2002).

  10. 10.

    Ekiert, D. C. et al. Cross-neutralization of influenza A viruses mediated by a single antibody loop. Nature 489, 526–532 (2012).

  11. 11.

    Hong, M. et al. Antibody recognition of the pandemic H1N1 influenza virus hemagglutinin receptor binding site. J. Virol. 87, 12471–12480 (2013).

  12. 12.

    Krause, J. C. et al. Human monoclonal antibodies to pandemic 1957 H2N2 and pandemic 1968 H3N2 influenza viruses. J. Virol. 86, 6334–6340 (2012).

  13. 13.

    Krause, J. C. et al. A broadly neutralizing human monoclonal antibody that recognizes a conserved, novel epitope on the globular head of the influenza H1N1 virus hemagglutinin. J. Virol. 85, 10905–10908 (2011).

  14. 14.

    Lee, P. S. et al. Receptor mimicry by antibody F045-092 facilitates universal binding to the H3 subtype of influenza virus. Nat. Commun. 5, 3614 (2014).

  15. 15.

    Lee, P. S. et al. Heterosubtypic antibody recognition of the influenza virus hemagglutinin receptor binding site enhanced by avidity. Proc. Natl Acad. Sci. USA 109, 17040–17045 (2012).

  16. 16.

    Ohshima, N. et al. Naturally occurring antibodies in humans can neutralize a variety of influenza virus strains, including H3, H1, H2, and H5. J. Virol. 85, 11048–11057 (2011).

  17. 17.

    Schmidt, A. G. et al. Preconfiguration of the antigen-binding site during affinity maturation of a broadly neutralizing influenza virus antibody. Proc. Natl Acad. Sci. USA 110, 264–269 (2013).

  18. 18.

    Whittle, J. R. et al. Broadly neutralizing human antibody that recognizes the receptor-binding pocket of influenza virus hemagglutinin. Proc. Natl Acad. Sci. USA 108, 14216–14221 (2011). This study identifies a broadly neutralizing pan-H1N1 antibody and shows, by crystallography, that this antibody recognizes the receptor binding site in the HA head, mimicking the interaction between the receptor and its natural substrate, sialic acid.

  19. 19.

    Xu, R. et al. A recurring motif for antibody recognition of the receptor-binding site of influenza hemagglutinin. Nat. Struct. Mol. Biol. 20, 363–370 (2013).

  20. 20.

    Yoshida, R. et al. Cross-protective potential of a novel monoclonal antibody directed against antigenic site B of the hemagglutinin of influenza A viruses. PLOS Pathog. 5, e1000350 (2009).

  21. 21.

    Corti, D. et al. A neutralizing antibody selected from plasma cells that binds to group 1 and group 2 influenza A hemagglutinins. Science 333, 850–856 (2011).

  22. 22.

    Dreyfus, C., Ekiert, D. C. & Wilson, I. A. Structure of a classical broadly neutralizing stem antibody in complex with a pandemic H2 influenza virus hemagglutinin. J. Virol. 87, 7149–7154 (2013).

  23. 23.

    Dreyfus, C. et al. Highly conserved protective epitopes on influenza B viruses. Science 337, 1343–1348 (2012). This study identifies human monoclonal antibodies that protect against lethal virus challenge from both influenza B lineages and shows that one antibody, CR9114, recognizes a conserved HA stem epitope and protects against both influenza A and influenza B viruses.

  24. 24.

    Ekiert, D. C. et al. Antibody recognition of a highly conserved influenza virus epitope. Science 324, 246–251 (2009). This study delineates the crystal structures of HA complexed with a broadly neutralizing antibody, CR6261, and identifies the highly conserved neutralizing epitope in the HA stem.

  25. 25.

    Ekiert, D. C. et al. A highly conserved neutralizing epitope on group 2 influenza A viruses. Science 333, 843–850 (2011).

  26. 26.

    Friesen, R. H. et al. A common solution to group 2 influenza virus neutralization. Proc. Natl Acad. Sci. USA 111, 445–450 (2014).

  27. 27.

    Fu, Y. et al. A broadly neutralizing anti-influenza antibody reveals ongoing capacity of haemagglutinin-specific memory B cells to evolve. Nat. Commun. 7, 12780 (2016).

  28. 28.

    Joyce, M. G. et al. Vaccine-induced antibodies that neutralize group 1 and group 2 influenza A viruses. Cell 166, 609–623 (2016). This study isolates both group 1 and group 2 influenza A neutralizing antibodies from H5N1 vaccinees and delineates the sequence signatures required for the generation of these antibodies.

  29. 29.

    Kallewaard, N. L. et al. Structure and function analysis of an antibody recognizing all influenza A subtypes. Cell 166, 596–608 (2016).

  30. 30.

    Kashyap, A. K. et al. Combinatorial antibody libraries from survivors of the Turkish H5N1 avian influenza outbreak reveal virus neutralization strategies. Proc. Natl Acad. Sci. USA 105, 5986–5991 (2008).

  31. 31.

    Nakamura, G. et al. An in vivo human-plasmablast enrichment technique allows rapid identification of therapeutic influenza A antibodies. Cell Host Microbe 14, 93–103 (2013).

  32. 32.

    Okuno, Y., Isegawa, Y., Sasao, F. & Ueda, S. A common neutralizing epitope conserved between the hemagglutinins of influenza A virus H1 and H2 strains. J. Virol. 67, 2552–2558 (1993). This study identifies a conserved stem neutralizing epitope for a cross-reactive pan-group 1 HA antibody, C179, derived from mice.

  33. 33.

    Sui, J. et al. Structural and functional bases for broad-spectrum neutralization of avian and human influenza A viruses. Nat. Struct. Mol. Biol. 16, 265–273 (2009). This study isolates a family of broadly neutralizing antibodies, including F10, that recognize a highly conserved epitope within the HA stem and shows that these antibodies are protective against both highly pathogenic H1N1 and H5N1 viruses in animal models.

  34. 34.

    Throsby, M. et al. Heterosubtypic neutralizing monoclonal antibodies cross-protective against H5N1 and H1N1 recovered from human IgM+ memory B cells. PLOS ONE 3, e3942 (2008).

  35. 35.

    Wu, Y. et al. A potent broad-spectrum protective human monoclonal antibody crosslinking two haemagglutinin monomers of influenza A virus. Nat. Commun. 6, 7708 (2015).

  36. 36.

    Wang, T. T. et al. Broadly protective monoclonal antibodies against H3 influenza viruses following sequential immunization with different hemagglutinins. PLOS Pathog. 6, e1000796 (2010).

  37. 37.

    Soema, P. C., Kompier, R., Amorij, J. P. & Kersten, G. F. Current and next generation influenza vaccines: formulation and production strategies. Eur. J. Pharm. Biopharm. 94, 251–263 (2015).

  38. 38.

    Dunkle, L. M. et al. Efficacy of recombinant influenza vaccine in adults 50 years of age or older. N. Engl. J. Med. 376, 2427–2436 (2017).

  39. 39.

    Sebastian, S. & Lambe, T. Clinical advances in viral-vectored influenza vaccines. Vaccines 6, E29 (2018).

  40. 40.

    Rajao, D. S. & Perez, D. R. Universal vaccines and vaccine platforms to protect against influenza viruses in humans and agriculture. Front. Microbiol. 9, 123 (2018).

  41. 41.

    Tong, S. et al. New world bats harbor diverse influenza A viruses. PLOS Pathog. 9, e1003657 (2013).

  42. 42.

    Hirst, G. K. The quantitative determination of influenza virus and antibodies by means of red cell agglutination. J. Exp. Med. 75, 49–64 (1942).

  43. 43.

    Hobson, D., Curry, R. L., Beare, A. S. & Ward-Gardner, A. The role of serum haemagglutination-inhibiting antibody in protection against challenge infection with influenza A2 and B viruses. J. Hyg. 70, 767–777 (1972).

  44. 44.

    Chen, Z., Zhou, H. & Jin, H. The impact of key amino acid substitutions in the hemagglutinin of influenza A (H3N2) viruses on vaccine production and antibody response. Vaccine 28, 4079–4085 (2010).

  45. 45.

    Raymond, D. D. et al. Influenza immunization elicits antibodies specific for an egg-adapted vaccine strain. Nat. Med. 22, 1465–1469 (2016).

  46. 46.

    Wilkinson, K. et al. Efficacy and safety of high-dose influenza vaccine in elderly adults: a systematic review and meta-analysis. Vaccine 35, 2775–2780 (2017).

  47. 47.

    Lee, J. K. H. et al. Efficacy and effectiveness of high-dose versus standard-dose influenza vaccination for older adults: a systematic review and meta-analysis. Expert. Rev. Vaccines 17, 435–443 (2018).

  48. 48.

    Camilloni, B., Basileo, M., Di Martino, A., Donatelli, I. & Iorio, A. M. Antibody responses to intradermal or intramuscular MF59-adjuvanted influenza vaccines as evaluated in elderly institutionalized volunteers during a season of partial mismatching between vaccine and circulating A(H3N2) strains. Immun. Ageing 11, 10 (2014).

  49. 49.

    Camilloni, B., Basileo, M., Valente, S., Nunzi, E. & Iorio, A. M. Immunogenicity of intramuscular MF59-adjuvanted and intradermal administered influenza enhanced vaccines in subjects aged over 60: a literature review. Hum. Vaccin. Immunother. 11, 553–563 (2015).

  50. 50.

    Darricarrere, N. et al. Development of a pan-H1 influenza vaccine. J. Virol. 92, e01349-18 (2018).

  51. 51.

    Carter, D. M. et al. Design and characterization of a computationally optimized broadly reactive hemagglutinin vaccine for H1N1 influenza viruses. J. Virol. 90, 4720–4734 (2016).

  52. 52.

    Elliott, S. T. C. et al. A synthetic micro-consensus DNA vaccine generates comprehensive influenza A H3N2 immunity and protects mice against lethal challenge by multiple H3N2 viruses. Hum. Gene Ther. 29, 1044–1055 (2018).

  53. 53.

    Giles, B. M. & Ross, T. M. A computationally optimized broadly reactive antigen (COBRA) based H5N1 VLP vaccine elicits broadly reactive antibodies in mice and ferrets. Vaccine 29, 3043–3054 (2011).

  54. 54.

    Ping, X. et al. Generation of a broadly reactive influenza H1 antigen using a consensus HA sequence. Vaccine 36, 4837–4845 (2018).

  55. 55.

    Wong, T. M. et al. Computationally optimized broadly reactive hemagglutinin elicits hemagglutination inhibition antibodies against a panel of H3N2 influenza virus cocirculating variants. J. Virol. 91, e01581-17 (2017).

  56. 56.

    Chen, M. W. et al. Broadly neutralizing DNA vaccine with specific mutation alters the antigenicity and sugar-binding activities of influenza hemagglutinin. Proc. Natl Acad. Sci. USA 108, 3510–3515 (2011).

  57. 57.

    Florek, N. W. et al. A modified vaccinia Ankara vaccine vector expressing a mosaic H5 hemagglutinin reduces viral shedding in rhesus macaques. PLOS ONE 12, e0181738 (2017).

  58. 58.

    Kamlangdee, A., Kingstad-Bakke, B., Anderson, T. K., Goldberg, T. L. & Osorio, J. E. Broad protection against avian influenza virus by using a modified vaccinia Ankara virus expressing a mosaic hemagglutinin gene. J. Virol. 88, 13300–13309 (2014).

  59. 59.

    Wei, C. J. et al. Induction of broadly neutralizing H1N1 influenza antibodies by vaccination. Science 329, 1060–1064 (2010). This study shows that a gene-based prime/protein boost approach increased the breadth of neutralization against diverse H1N1 viruses and demonstrates that stem-directed antibodies can be induced by vaccination.

  60. 60.

    Ledgerwood, J. E. et al. DNA priming and influenza vaccine immunogenicity: two phase 1 open label randomised clinical trials. Lancet Infect. Dis. 11, 916–924 (2011). This study shows in two phase I studies that DNA priming followed by a monovalent inactivated vaccine boost improved the neutralizing antibody response, and demonstrates that HA stem-directed antibodies can be induced by vaccination in humans.

  61. 61.

    Atsmon, J. et al. Priming by a novel universal influenza vaccine (Multimeric-001)—a gateway for improving immune response in the elderly population. Vaccine 32, 5816–5823 (2014).

  62. 62.

    Santos, J. J. S. et al. Development of an alternative modified live influenza B virus vaccine. J. Virol. 91, e00056-17 (2017).

  63. 63.

    Ducatez, M. F. et al. Low pathogenic avian influenza (H9N2) in chicken: evaluation of an ancestral H9-MVA vaccine. Vet. Microbiol. 189, 59–67 (2016).

  64. 64.

    Florek, N. W. et al. Modified vaccinia virus Ankara encoding influenza virus hemagglutinin induces heterosubtypic immunity in macaques. J. Virol. 88, 13418–13428 (2014).

  65. 65.

    Hessel, A. et al. MVA vectors expressing conserved influenza proteins protect mice against lethal challenge with H5N1, H9N2 and H7N1 viruses. PLOS ONE 9, e88340 (2014).

  66. 66.

    Lillie, P. J. et al. Preliminary assessment of the efficacy of a T-cell-based influenza vaccine, MVA-NP + M1, in humans. Clin. Infect. Dis. 55, 19–25 (2012).

  67. 67.

    Boyd, A. C. et al. Towards a universal vaccine for avian influenza: protective efficacy of modified vaccinia virus Ankara and adenovirus vaccines expressing conserved influenza antigens in chickens challenged with low pathogenic avian influenza virus. Vaccine 31, 670–675 (2013).

  68. 68.

    Crosby, C. M. et al. Replicating single-cycle adenovirus vectors generate amplified influenza vaccine responses. J. Virol. 91, e00720 (2017).

  69. 69.

    Wesley, R. D., Tang, M. & Lager, K. M. Protection of weaned pigs by vaccination with human adenovirus 5 recombinant viruses expressing the hemagglutinin and the nucleoprotein of H3N2 swine influenza virus. Vaccine 22, 3427–3434 (2004).

  70. 70.

    Kim, S. H., Paldurai, A. & Samal, S. K. A novel chimeric newcastle disease virus vectored vaccine against highly pathogenic avian influenza virus. Virology 503, 31–36 (2017).

  71. 71.

    Liu, Q. et al. Newcastle disease virus-vectored H7 and H5 live vaccines protect chickens from challenge with H7N9 or H5N1 avian influenza viruses. J. Virol. 89, 7401–7408 (2015).

  72. 72.

    Vander Veen, R. L. et al. Safety, immunogenicity, and efficacy of an alphavirus replicon-based swine influenza virus hemagglutinin vaccine. Vaccine 30, 1944–1950 (2012).

  73. 73.

    Vander Veen, R. L. et al. Haemagglutinin and nucleoprotein replicon particle vaccination of swine protects against the pandemic H1N1 2009 virus. Vet. Rec. 173, 344 (2013).

  74. 74.

    Antrobus, R. D. et al. Clinical assessment of a novel recombinant simian adenovirus ChAdOx1 as a vectored vaccine expressing conserved influenza A antigens. Mol. Ther. 22, 668–674 (2014).

  75. 75.

    Hubby, B. et al. Development and preclinical evaluation of an alphavirus replicon vaccine for influenza. Vaccine 25, 8180–8189 (2007).

  76. 76.

    Kreijtz, J. H. et al. Safety and immunogenicity of a modified-vaccinia-virus-Ankara-based influenza A H5N1 vaccine: a randomised, double-blind phase 1/2a clinical trial. Lancet Infect. Dis. 14, 1196–1207 (2014).

  77. 77.

    Liebowitz, D., Lindbloom, J. D., Brandl, J. R., Garg, S. J. & Tucker, S. N. High titre neutralising antibodies to influenza after oral tablet immunisation: a phase 1, randomised, placebo-controlled trial. Lancet Infect. Dis. 15, 1041–1048 (2015).

  78. 78.

    Pardi, N. et al. Nucleoside-modified mRNA immunization elicits influenza virus hemagglutinin stalk-specific antibodies. Nat. Commun. 9, 3361 (2018).

  79. 79.

    Low, J. G. et al. Safety and immunogenicity of a virus-like particle pandemic influenza A (H1N1) 2009 vaccine: results from a double-blinded, randomized phase I clinical trial in healthy Asian volunteers. Vaccine 32, 5041–5048 (2014).

  80. 80.

    Pillet, S. et al. A plant-derived quadrivalent virus like particle influenza vaccine induces cross-reactive antibody and T cell response in healthy adults. Clin. Immunol. 168, 72–87 (2016).

  81. 81.

    Valero-Pacheco, N. et al. Antibody persistence in adults 2 years after vaccination with an H1N1 2009 pandemic influenza virus-like particle vaccine. PLOS ONE 11, e0150146 (2016).

  82. 82.

    Fries, L. F., Smith, G. E. & Glenn, G. M. A recombinant viruslike particle influenza A (H7N9) vaccine. N. Engl. J. Med. 369, 2564–2566 (2013).

  83. 83.

    Lowell, G. H., Ziv, S., Bruzil, S., Babecoff, R. & Ben-Yedidia, T. Back to the future: immunization with M-001 prior to trivalent influenza vaccine in 2011/12 enhanced protective immune responses against 2014/15 epidemic strain. Vaccine 35, 713–715 (2017).

  84. 84.

    van Doorn, E. et al. Evaluating the immunogenicity and safety of a BiondVax-developed universal influenza vaccine (Multimeric-001) either as a standalone vaccine or as a primer to H5N1 influenza vaccine: phase IIb study protocol. Medicine 96, e6339 (2017).

  85. 85.

    van Doorn, E. et al. Evaluation of the immunogenicity and safety of different doses and formulations of a broad spectrum influenza vaccine (FLU-v) developed by SEEK: study protocol for a single-center, randomized, double-blind and placebo-controlled clinical phase IIb trial. BMC Infect. Dis. 17, 241 (2017).

  86. 86.

    Hatta, Y. et al. M2SR, a novel live influenza vaccine, protects mice and ferrets against highly pathogenic avian influenza. Vaccine 35, 4177–4183 (2017).

  87. 87.

    Sarawar, S. et al. M2SR, a novel live single replication influenza virus vaccine, provides effective heterosubtypic protection in mice. Vaccine 34, 5090–5098 (2016).

  88. 88.

    Kanekiyo, M. et al. Self-assembling influenza nanoparticle vaccines elicit broadly neutralizing H1N1 antibodies. Nature 499, 102–106 (2013).

  89. 89.

    Daniels, R., Kurowski, B., Johnson, A. E. & Hebert, D. N. N-linked glycans direct the cotranslational folding pathway of influenza hemagglutinin. Mol. Cell 11, 79–90 (2003).

  90. 90.

    Gallagher, P. J., Henneberry, J. M., Sambrook, J. F. & Gething, M. J. Glycosylation requirements for intracellular transport and function of the hemagglutinin of influenza virus. J. Virol. 66, 7136–7145 (1992).

  91. 91.

    Wiley, D. C. & Skehel, J. J. The structure and function of the hemagglutinin membrane glycoprotein of influenza virus. Annu. Rev. Biochem. 56, 365–394 (1987). This seminal review article discusses the structure and function of influenza HA.

  92. 92.

    Wu, N. C. & Wilson, I. A. A perspective on the structural and functional constraints for immune evasion: insights from influenza virus. J. Mol. Biol. 429, 2694–2709 (2017).

  93. 93.

    Wei, C. J. et al. Cross-neutralization of 1918 and 2009 influenza viruses: role of glycans in viral evolution and vaccine design. Sci. Transl Med. 2, 24ra21 (2010).

  94. 94.

    Medina, R. A. et al. Glycosylations in the globular head of the hemagglutinin protein modulate the virulence and antigenic properties of the H1N1 influenza viruses. Sci. Transl Med. 5, 187ra170 (2013).

  95. 95.

    Treanor, J. J. Prospects for broadly protective influenza vaccines. Am. J. Prev. Med. 49, S355–S363 (2015).

  96. 96.

    Lee, P. S. & Wilson, I. A. Structural characterization of viral epitopes recognized by broadly cross-reactive antibodies. Curr. Top. Microbiol. Immunol. 386, 323–341 (2015).

  97. 97.

    Schmidt, A. G. et al. Viral receptor-binding site antibodies with diverse germline origins. Cell 161, 1026–1034 (2015).

  98. 98.

    Smirnov, Y. A. et al. An epitope shared by the hemagglutinins of H1, H2, H5, and H6 subtypes of influenza A virus. Acta Virol. 43, 237–244 (1999).

  99. 99.

    Sagawa, H., Ohshima, A., Kato, I., Okuno, Y. & Isegawa, Y. The immunological activity of a deletion mutant of influenza virus haemagglutinin lacking the globular region. J. Gen. Virol. 77, 1483–1487 (1996).

  100. 100.

    Tan, G. S. et al. Characterization of a broadly neutralizing monoclonal antibody that targets the fusion domain of group 2 influenza A virus hemagglutinin. J. Virol. 88, 13580–13592 (2014).

  101. 101.

    Rajendran, M. et al. Analysis of anti-influenza virus neuraminidase antibodies in children, adults, and the elderly by ELISA and enzyme inhibition: evidence for original antigenic sin. MBio 8, e02281-16 (2017).

  102. 102.

    Wohlbold, T. J. et al. Hemagglutinin stalk- and neuraminidase-specific monoclonal antibodies protect against lethal H10N8 influenza virus infection in mice. J. Virol. 90, 851–861 (2016).

  103. 103.

    Andrews, S. F. et al. Preferential induction of cross-group influenza A hemagglutinin stem-specific memory B cells after H7N9 immunization in humans. Sci. Immunol. 2, eaan2676 (2017).

  104. 104.

    Krammer, F. et al. An H7N1 influenza virus vaccine induces broadly reactive antibody responses against H7N9 in humans. Clin. Vaccine Immunol. 21, 1153–1163 (2014).

  105. 105.

    Ellebedy, A. H. et al. Induction of broadly cross-reactive antibody responses to the influenza HA stem region following H5N1 vaccination in humans. Proc. Natl Acad. Sci. USA 111, 13133–13138 (2014).

  106. 106.

    Nachbagauer, R. et al. Induction of broadly reactive anti-hemagglutinin stalk antibodies by an H5N1 vaccine in humans. J. Virol. 88, 13260–13268 (2014).

  107. 107.

    Khurana, S. et al. AS03-adjuvanted H5N1 vaccine promotes antibody diversity and affinity maturation, NAI titers, cross-clade H5N1 neutralization, but not H1N1 cross-subtype neutralization. NPJ Vaccines 3, 40 (2018).

  108. 108.

    Sui, J. et al. Wide prevalence of heterosubtypic broadly neutralizing human anti-influenza A antibodies. Clin. Infect. Dis. 52, 1003–1009 (2011).

  109. 109.

    Yassine, H. M. et al. Use of hemagglutinin stem probes demonstrate prevalence of broadly reactive group 1 influenza antibodies in human sera. Sci. Rep. 8, 8628 (2018).

  110. 110.

    Hai, R. et al. Influenza viruses expressing chimeric hemagglutinins: globular head and stalk domains derived from different subtypes. J. Virol. 86, 5774–5781 (2012).

  111. 111.

    Krammer, F. et al. H3 stalk-based chimeric hemagglutinin influenza virus constructs protect mice from H7N9 challenge. J. Virol. 88, 2340–2343 (2014).

  112. 112.

    Krammer, F., Pica, N., Hai, R., Margine, I. & Palese, P. Chimeric hemagglutinin influenza virus vaccine constructs elicit broadly protective stalk-specific antibodies. J. Virol. 87, 6542–6550 (2013).

  113. 113.

    Margine, I. et al. Hemagglutinin stalk-based universal vaccine constructs protect against group 2 influenza A viruses. J. Virol. 87, 10435–10446 (2013).

  114. 114.

    Bernstein, D. I. et al. Immunogenicity of chimeric haemagglutinin-based, universal influenza virus vaccine candidates: interim results of a randomised, placebo-controlled, phase 1 clinical trial. Lancet Infect. Dis. 20, 80–91 (2020).

  115. 115.

    Broecker, F. et al. A mosaic hemagglutinin-based influenza virus vaccine candidate protects mice from challenge with divergent H3N2 strains. NPJ Vaccines 4, 31 (2019).

  116. 116.

    Krammer, F. & Palese, P. Universal influenza virus vaccines that target the conserved hemagglutinin stalk and conserved sites in the head domain. J. Infect. Dis. 219, S62–S67 (2019).

  117. 117.

    Sun, W. et al. Development of influenza B universal vaccine candidates using the “mosaic” hemagglutinin approach. J. Virol. 93, e00333-19 (2019).

  118. 118.

    Yassine, H. M. et al. Hemagglutinin-stem nanoparticles generate heterosubtypic influenza protection. Nat. Med. 21, 1065–1070 (2015). This study reports on the rational designs of an HA stem immunogen that can be displayed on a self-assembling nanoparticle and shows that this vaccine induced stem-directed antibodies and protected against heterologous viral challenges in animal models.

  119. 119.

    Impagliazzo, A. et al. A stable trimeric influenza hemagglutinin stem as a broadly protective immunogen. Science 349, 1301–1306 (2015). This study describes the development of a second HA stem immunogen that elicited broadly reactive antibodies and protected mice from heterologous viral challenge.

  120. 120.

    Corbett, K. S. et al. Design of nanoparticulate group 2 influenza virus hemagglutinin stem antigens that activate unmutated ancestor B cell receptors of broadly neutralizing antibody lineages. MBio 10, e02810-18 (2019).

  121. 121.

    National Institutes of Health. Influenza HA ferritin vaccine, alone or in prime-boost regimens with an influenza DNA vaccine in healthy adults https://clinicaltrials.gov/ct2/show/NCT03186781?cond=h03186782n03186782&rank=03186785 (2017).

  122. 122.

    Bangaru, S. et al. A multifunctional human monoclonal neutralizing antibody that targets a unique conserved epitope on influenza HA. Nat. Commun. 9, 2669 (2018).

  123. 123.

    Kanekiyo, M. et al. Mosaic nanoparticle display of diverse influenza virus hemagglutinins elicits broad B cell responses. Nat. Immunol. 20, 362–372 (2019).

  124. 124.

    Raymond, D. D. et al. Conserved epitope on influenza-virus hemagglutinin head defined by a vaccine-induced antibody. Proc. Natl Acad. Sci. USA 115, 168–173 (2018).

  125. 125.

    Bangaru, S. et al. A site of vulnerability on the influenza virus hemagglutinin head domain trimer interface. Cell 177, 1136–1152.e18 (2019). This study describes a human monoclonal antibody that recognized a conserved site on the trimer interface of the HA head. This antibody inhibited virus spread and protected mice against virus challenge, possibly by disrupting the HA trimer structural integrity.

  126. 126.

    Watanabe, A. et al. Antibodies to a conserved influenza head interface epitope protect by an IgG subtype-dependent mechanism. Cell 177, 1124–1135.e16 (2019).

  127. 127.

    Memoli, M. J. et al. Evaluation of antihemagglutinin and antineuraminidase antibodies as correlates of protection in an influenza A/H1N1 virus healthy human challenge model. MBio 7, e00417-16 (2016).

  128. 128.

    Couch, R. B. et al. Antibody correlates and predictors of immunity to naturally occurring influenza in humans and the importance of antibody to the neuraminidase. J. Infect. Dis. 207, 974–981 (2013).

  129. 129.

    Monto, A. S. et al. Antibody to influenza virus neuraminidase: an independent correlate of protection. J. Infect. Dis. 212, 1191–1199 (2015).

  130. 130.

    Colman, P. M. Influenza virus neuraminidase: structure, antibodies, and inhibitors. Protein Sci. 3, 1687–1696 (1994).

  131. 131.

    Marcelin, G. et al. A contributing role for anti-neuraminidase antibodies on immunity to pandemic H1N1 2009 influenza A virus. PLOS ONE 6, e26335 (2011).

  132. 132.

    Sandbulte, M. R. et al. Cross-reactive neuraminidase antibodies afford partial protection against H5N1 in mice and are present in unexposed humans. PLOS Med. 4, e59 (2007).

  133. 133.

    Wan, H. et al. Molecular basis for broad neuraminidase immunity: conserved epitopes in seasonal and pandemic H1N1 as well as H5N1 influenza viruses. J. Virol. 87, 9290–9300 (2013).

  134. 134.

    Wohlbold, T. J. et al. Vaccination with adjuvanted recombinant neuraminidase induces broad heterologous, but not heterosubtypic, cross-protection against influenza virus infection in mice. MBio 6, e02556 (2015).

  135. 135.

    Eichelberger, M. C. & Monto, A. S. Neuraminidase, the forgotten surface antigen, emerges as an influenza vaccine target for broadened protection. J. Infect. Dis. 219, S75–S80 (2019).

  136. 136.

    Samson, M. et al. Characterization of drug-resistant influenza virus A(H1N1) and A(H3N2) variants selected in vitro with laninamivir. Antimicrob. Agents Chemother. 58, 5220–5228 (2014).

  137. 137.

    Stadlbauer, D. et al. Broadly protective human antibodies that target the active site of influenza virus neuraminidase. Science 366, 499–504 (2019). This study isolates human monoclonal antibodies that broadly react with multiple influenza A and influenza B neuraminidases and protected against both influenza A and influenza B virus challenge in animal models.

  138. 138.

    Schulman, J. L. & Kilbourne, E. D. Independent variation in nature of hemagglutinin and neuraminidase antigens of influenza virus: distinctiveness of hemagglutinin antigen of Hong Kong-68 virus. Proc. Natl Acad. Sci. USA 63, 326–333 (1969).

  139. 139.

    Monto, A. S. & Kendal, A. P. Effect of neuraminidase antibody on Hong Kong influenza. Lancet 1, 623–625 (1973).

  140. 140.

    Murphy, B. R., Kasel, J. A. & Chanock, R. M. Association of serum anti-neuraminidase antibody with resistance to influenza in man. N. Engl. J. Med. 286, 1329–1332 (1972).

  141. 141.

    Johansson, B. E. & Cox, M. M. Influenza viral neuraminidase: the forgotten antigen. Expert. Rev. Vaccines 10, 1683–1695 (2011).

  142. 142.

    Krammer, F. & Palese, P. Advances in the development of influenza virus vaccines. Nat. Rev. Drug. Discov. 14, 167–182 (2015).

  143. 143.

    Job, E. R. et al. Broadened immunity against influenza by vaccination with computationally designed influenza virus N1 neuraminidase constructs. NPJ Vaccines 3, 55 (2018).

  144. 144.

    Kolpe, A., Schepens, B., Fiers, W. & Saelens, X. M2-based influenza vaccines: recent advances and clinical potential. Expert. Rev. Vaccines 16, 123–136 (2017).

  145. 145.

    Neirynck, S. et al. A universal influenza A vaccine based on the extracellular domain of the M2 protein. Nat. Med. 5, 1157–1163 (1999).

  146. 146.

    Turley, C. B. et al. Safety and immunogenicity of a recombinant M2e–flagellin influenza vaccine (STF2.4xM2e) in healthy adults. Vaccine 29, 5145–5152 (2011).

  147. 147.

    Huleatt, J. W. et al. Potent immunogenicity and efficacy of a universal influenza vaccine candidate comprising a recombinant fusion protein linking influenza M2e to the TLR5 ligand flagellin. Vaccine 26, 201–214 (2008).

  148. 148.

    Bernasconi, V. et al. Porous nanoparticles with self-adjuvanting M2e-fusion protein and recombinant hemagglutinin provide strong and broadly protective immunity against influenza virus infections. Front. Immunol. 9, 2060 (2018).

  149. 149.

    El Bakkouri, K. et al. Universal vaccine based on ectodomain of matrix protein 2 of influenza A: Fc receptors and alveolar macrophages mediate protection. J. Immunol. 186, 1022–1031 (2011).

  150. 150.

    Ramos, E. L. et al. Efficacy and safety of treatment with an anti-m2e monoclonal antibody in experimental human influenza. J. Infect. Dis. 211, 1038–1044 (2015).

  151. 151.

    Zharikova, D., Mozdzanowska, K., Feng, J., Zhang, M. & Gerhard, W. Influenza type A virus escape mutants emerge in vivo in the presence of antibodies to the ectodomain of matrix protein 2. J. Virol. 79, 6644–6654 (2005).

  152. 152.

    Morabito, K. M. et al. Memory inflation drives tissue-resident memory CD8+ T cell maintenance in the lung after intranasal vaccination with murine cytomegalovirus. Front. Immunol. 9, 1861 (2018).

  153. 153.

    Koutsakos, M., Nguyen, T. H. O. & Kedzierska, K. With a little help from T follicular helper friends: humoral immunity to influenza vaccination. J. Immunol. 202, 360–367 (2019).

  154. 154.

    Schulman, J. L. & Kilbourne, E. D. Induction of partial specific heterotypic immunity in mice by a single infection with influenza a virus. J. Bacteriol. 89, 170–174 (1965).

  155. 155.

    Seo, S. H., Peiris, M. & Webster, R. G. Protective cross-reactive cellular immunity to lethal A/Goose/Guangdong/1/96-like H5N1 influenza virus is correlated with the proportion of pulmonary CD8+ T cells expressing γ interferon. J. Virol. 76, 4886–4890 (2002).

  156. 156.

    Straight, T. M., Ottolini, M. G., Prince, G. A. & Eichelberger, M. C. Evidence of a cross-protective immune response to influenza A in the cotton rat model. Vaccine 24, 6264–6271 (2006).

  157. 157.

    Weinfurter, J. T. et al. Cross-reactive T cells are involved in rapid clearance of 2009 pandemic H1N1 influenza virus in nonhuman primates. PLOS Pathog. 7, e1002381 (2011).

  158. 158.

    Yetter, R. A., Barber, W. H. & Small, P. A. Jr. Heterotypic immunity to influenza in ferrets. Infect. Immun. 29, 650–653 (1980).

  159. 159.

    Sant, A. J. The way forward: potentiating protective immunity to novel and pandemic influenza through engagement of memory CD4 T cells. J. Infect. Dis. 219, S30–S37 (2019).

  160. 160.

    Altenburg, A. F., Rimmelzwaan, G. F. & de Vries, R. D. Virus-specific T cells as correlate of (cross-)protective immunity against influenza. Vaccine 33, 500–506 (2015).

  161. 161.

    Sridhar, S. et al. Cellular immune correlates of protection against symptomatic pandemic influenza. Nat. Med. 19, 1305–1312 (2013).

  162. 162.

    Wilkinson, T. M. et al. Preexisting influenza-specific CD4+ T cells correlate with disease protection against influenza challenge in humans. Nat. Med. 18, 274–280 (2012).

  163. 163.

    Antrobus, R. D. et al. Coadministration of seasonal influenza vaccine and MVA-NP + M1 simultaneously achieves potent humoral and cell-mediated responses. Mol. Ther. 22, 233–238 (2014).

  164. 164.

    Mullarkey, C. E. et al. Improved adjuvanting of seasonal influenza vaccines: preclinical studies of MVA-NP + M1 coadministration with inactivated influenza vaccine. Eur. J. Immunol. 43, 1940–1952 (2013).

  165. 165.

    Antrobus, R. D. et al. A T cell-inducing influenza vaccine for the elderly: safety and immunogenicity of MVA-NP + M1 in adults aged over 50 years. PLOS ONE 7, e48322 (2012).

  166. 166.

    Rimmelzwaan, G. F. & Sutter, G. Candidate influenza vaccines based on recombinant modified vaccinia virus Ankara. Expert. Rev. Vaccines 8, 447–454 (2009).

  167. 167.

    Tregoning, J. S., Russell, R. F. & Kinnear, E. Adjuvanted influenza vaccines. Hum. Vaccin. Immunother. 14, 550–564 (2018). This article reviews clinical experiences with adjuvants for influenza vaccines and discusses the mode of action of commonly used vaccine adjuvants and their effects on vaccine safety and immunogenicity.

  168. 168.

    Petrovsky, N. Comparative safety of vaccine adjuvants: a summary of current evidence and future needs. Drug. Saf. 38, 1059–1074 (2015).

  169. 169.

    Bernstein, D. I. et al. Effects of adjuvants on the safety and immunogenicity of an avian influenza H5N1 vaccine in adults. J. Infect. Dis. 197, 667–675 (2008).

  170. 170.

    Manzoli, L. et al. Meta-analysis of the immunogenicity and tolerability of pandemic influenza A 2009 (H1N1) vaccines. PLOS ONE 6, e24384 (2011).

  171. 171.

    Del Giudice, G. & Rappuoli, R. Inactivated and adjuvanted influenza vaccines. Curr. Top. Microbiol. Immunol. 386, 151–180 (2015).

  172. 172.

    Caillet, C. et al. AF03-adjuvanted and non-adjuvanted pandemic influenza A (H1N1) 2009 vaccines induce strong antibody responses in seasonal influenza vaccine-primed and unprimed mice. Vaccine 28, 3076–3079 (2010).

  173. 173.

    McElhaney, J. E. et al. AS03-adjuvanted versus non-adjuvanted inactivated trivalent influenza vaccine against seasonal influenza in elderly people: a phase 3 randomised trial. Lancet Infect. Dis. 13, 485–496 (2013).

  174. 174.

    Schwarz, T. F. et al. Single dose vaccination with AS03-adjuvanted H5N1 vaccines in a randomized trial induces strong and broad immune responsiveness to booster vaccination in adults. Vaccine 27, 6284–6290 (2009).

  175. 175.

    Liu, Y. V. et al. Recombinant virus-like particles elicit protective immunity against avian influenza A(H7N9) virus infection in ferrets. Vaccine 33, 2152–2158 (2015).

  176. 176.

    Bonam, S. R., Partidos, C. D., Halmuthur, S. K. M. & Muller, S. An overview of novel adjuvants designed for improving vaccine efficacy. Trends Pharmacol. Sci. 38, 771–793 (2017).

  177. 177.

    Treanor, J. J. et al. Evaluation of safety and immunogenicity of recombinant influenza hemagglutinin (H5/Indonesia/05/2005) formulated with and without a stable oil-in-water emulsion containing glucopyranosyl-lipid A (SE + GLA) adjuvant. Vaccine 31, 5760–5765 (2013).

  178. 178.

    Clegg, C. H. et al. GLA-AF, an emulsion-free vaccine adjuvant for pandemic influenza. PLOS ONE 9, e88979 (2014).

  179. 179.

    Desbien, A. L. et al. Squalene emulsion potentiates the adjuvant activity of the TLR4 agonist, GLA, via inflammatory caspases, IL-18, and IFN-γ. Eur. J. Immunol. 45, 407–417 (2015).

  180. 180.

    Taylor, D. N. et al. Induction of a potent immune response in the elderly using the TLR-5 agonist, flagellin, with a recombinant hemagglutinin influenza–flagellin fusion vaccine (VAX125, STF2.HA1 SI). Vaccine 29, 4897–4902 (2011).

  181. 181.

    Van Hoeven, N. et al. A formulated TLR7/8 agonist is a flexible, highly potent and effective adjuvant for pandemic influenza vaccines. Sci. Rep. 7, 46426 (2017).

  182. 182.

    Hartmann, G. et al. Delineation of a CpG phosphorothioate oligodeoxynucleotide for activating primate immune responses in vitro and in vivo. J. Immunol. 164, 1617–1624 (2000).

  183. 183.

    Klinman, D. M., Yi, A. K., Beaucage, S. L., Conover, J. & Krieg, A. M. CpG motifs present in bacteria DNA rapidly induce lymphocytes to secrete interleukin 6, interleukin 12, and interferon γ. Proc. Natl Acad. Sci. USA 93, 2879–2883 (1996).

  184. 184.

    Krug, A. et al. CpG-A oligonucleotides induce a monocyte-derived dendritic cell-like phenotype that preferentially activates CD8 T cells. J. Immunol. 170, 3468–3477 (2003).

  185. 185.

    Fang, Y. et al. Molecular characterization of in vivo adjuvant activity in ferrets vaccinated against influenza virus. J. Virol. 84, 8369–8388 (2010).

  186. 186.

    Cooper, C. L. et al. Safety and immunogenicity of CPG 7909 injection as an adjuvant to fluarix influenza vaccine. Vaccine 22, 3136–3143 (2004).

  187. 187.

    World Heath Organisation. Global vaccine market features and trends. https://www.who.int/influenza_vaccines_plan/resources/session_10_kaddar.pdf. (WHO, 2012).

  188. 188.

    Centers for Disease Control and Prevention. How influenza (flu) vaccine are made https://www.cdc.gov/flu/prevent/vaccine/how-fluvaccine-made.htm. (CDC, 2019).

  189. 189.

    Centers for Disease Control and Prevention. Vaccine effectiveness—how well does the flu vaccine work https://www.cdc.gov/flu/vaccines-work/vaccineeffect.htm (CDC, 2020).

  190. 190.

    Food and Drug Administration. Clinical data needed to support the licensure of seasonal inactivated influenza vaccines https://www.fda.gov/downloads/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Guidances/Vaccines/ucm091990.pdf (FDA, 2007).

  191. 191.

    Wood, J. M. & Levandowski, R. A. The influenza vaccine licensing process. Vaccine 21, 1786–1788 (2003).

  192. 192.

    Food and Drug Administration. Clinical data needed to support the licensure of pandemic influenza vaccines https://www.fda.gov/downloads/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Guidances/Vaccines/ucm091985.pdf (FDA, 2007).

  193. 193.

    [No authors listed]. AGGLUTINATION-INHIBITION test proposed as a standard of reference in influenza diagnostic studies; Committee on Standard Serological Procedures in Influenza Studies. J. Immunol. 65, 347–353 (1950).

  194. 194.

    Jegaskanda, S., Vanderven, H. A., Wheatley, A. K. & Kent, S. J. Fc or not Fc; that is the question: antibody Fc-receptor interactions are key to universal influenza vaccine design. Hum. Vaccin. Immunother. 13, 1–9 (2017).

  195. 195.

    Friedewald, W. F. Qualitative differences in the antigenic composition of influenza a virus strains. J. Exp. Med. 79, 633–647 (1944).

  196. 196.

    Walker, D. L. & Horsfall, F. L. Jr. Lack of identity in neutralizing and hemagglutination-inhibiting antibodies against influenza viruses. J. Exp. Med. 91, 65–86 (1950).

  197. 197.

    Allen, J. D. & Ross, T. M. H3N2 influenza viruses in humans: viral mechanisms, evolution, and evaluation. Hum. Vaccin. Immunother. 14, 1840–1847 (2018).

  198. 198.

    Whittle, J. R. et al. Flow cytometry reveals that H5N1 vaccination elicits cross-reactive stem-directed antibodies from multiple Ig heavy-chain lineages. J. Virol. 88, 4047–4057 (2014).

  199. 199.

    Andrews, S. F., Graham, B. S., Mascola, J. R. & McDermott, A. B. Is it possible to develop a “universal” influenza virus vaccine? Immunogenetic considerations underlying B-cell biology in the development of a pan-subtype influenza A vaccine targeting the hemagglutinin stem. Cold Spring Harb. Perspect. Biol. 10, a029413 (2018).

  200. 200.

    Kwong, P. D. & Mascola, J. R. HIV-1 vaccines based on antibody identification, B cell ontogeny, and epitope structure. Immunity 48, 855–871 (2018).

  201. 201.

    Deng, L., Cho, K. J., Fiers, W. & Saelens, X. M2e-based universal influenza A vaccines. Vaccines 3, 105–136 (2015).

  202. 202.

    Mohn, K. G., Smith, I., Sjursen, H. & Cox, R. J. Immune responses after live attenuated influenza vaccination. Hum. Vaccin. Immunother. 14, 571–578 (2018).

  203. 203.

    Wong, S. S. & Webby, R. J. Traditional and new influenza vaccines. Clin. Microbiol. Rev. 26, 476–492 (2013).

  204. 204.

    Memoli, M. J. et al. Validation of the wild-type influenza A human challenge model H1N1pdMIST: an A(H1N1)pdm09 dose-finding investigational new drug study. Clin. Infect. Dis. 60, 693–702 (2015).

  205. 205.

    National Institute of Allergy and Infectious Diseases. NIAID adds influenza vaccine research to omnibus solicitation https://www.niaid.nih.gov/grants-contracts/influenza-vaccine-research-solicitation (NIAID, 2018).

  206. 206.

    Han, A. et al. Using the influenza patient-reported outcome (FLU-PRO) diary to evaluate symptoms of influenza viral infection in a healthy human challenge model. BMC Infect. Dis. 18, 353 (2018).

  207. 207.

    Park, J. K. et al. Evaluation of preexisting anti-hemagglutinin stalk antibody as a correlate of protection in a healthy volunteer challenge with influenza A/H1N1pdm virus. MBio 9, e02284-17 (2018).

  208. 208.

    Food and Drug Administration. Food and Drug Administration Amendments Act (FDAAA) of 2007 https://www.fda.gov/RegulatoryInformation/LawsEnforcedbyFDA/SignificantAmendmentstotheFDCAct/FoodandDrugAdministrationAmendmentsActof2007/default.htm (FDA, 2007).

  209. 209.

    Centers for Disease Control and Prevention. Licensure of a high-dose inactivated influenza vaccine for persons aged ≥65 years (Fluzone High-Dose) and guidance for use https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5916a2.htm (CDC, 2010).

  210. 210.

    DiazGranados, C. A. et al. Efficacy of high-dose versus standard-dose influenza vaccine in older adults. N. Engl. J. Med. 371, 635–645 (2014).

  211. 211.

    Izurieta, H. S. et al. Comparative effectiveness of high-dose versus standard-dose influenza vaccines in US residents aged 65 years and older from 2012 to 2013 using Medicare data: a retrospective cohort analysis. Lancet Infect. Dis. 15, 293–300 (2015).

  212. 212.

    Kim, J. H. et al. High-dose influenza vaccine favors acute plasmablast responses rather than long-term cellular responses. Vaccine 34, 4594–4601 (2016).

  213. 213.

    Fukushima, W. & Hirota, Y. Basic principles of test-negative design in evaluating influenza vaccine effectiveness. Vaccine 35, 4796–4800 (2017).

  214. 214.

    McLean, K. A., Goldin, S., Nannei, C., Sparrow, E. & Torelli, G. The 2015 global production capacity of seasonal and pandemic influenza vaccine. Vaccine 34, 5410–5413 (2016).

  215. 215.

    Perez Rubio, A. & Eiros, J. M. Cell culture-derived flu vaccine: present and future. Hum. Vaccin. Immunother. 14, 1874–1882 (2018).

  216. 216.

    Cox, M. M., Izikson, R., Post, P. & Dunkle, L. Safety, efficacy, and immunogenicity of Flublok in the prevention of seasonal influenza in adults. Ther. Adv. Vaccines 3, 97–108 (2015).

  217. 217.

    Tapia, F., Vazquez-Ramirez, D., Genzel, Y. & Reichl, U. Bioreactors for high cell density and continuous multi-stage cultivations: options for process intensification in cell culture-based viral vaccine production. Appl. Microbiol. Biotechnol. 100, 2121–2132 (2016).

  218. 218.

    Carter, C. et al. Safety and immunogenicity of investigational seasonal influenza hemagglutinin DNA vaccine followed by trivalent inactivated vaccine administered intradermally or intramuscularly in healthy adults: an open-label randomized phase 1 clinical trial. PLOS ONE 14, e0222178 (2019).

  219. 219.

    Crank, M. C. et al. Phase 1 study of pandemic H1 DNA vaccine in healthy adults. PLOS ONE 10, e0123969 (2015).

  220. 220.

    DeZure, A. D. et al. An avian influenza H7 DNA priming vaccine is safe and immunogenic in a randomized phase I clinical trial. NPJ Vaccines 2, 15 (2017).

  221. 221.

    Houser, K. V. et al. DNA vaccine priming for seasonal influenza vaccine in children and adolescents 6 to 17 years of age: a phase 1 randomized clinical trial. PLOS ONE 13, e0206837 (2018).

  222. 222.

    Ledgerwood, J. E. et al. DNA priming for seasonal influenza vaccine: a phase 1b double-blind randomized clinical trial. PLOS ONE 10, e0125914 (2015).

  223. 223.

    Ledgerwood, J. E. et al. Phase I clinical evaluation of seasonal influenza hemagglutinin (HA) DNA vaccine prime followed by trivalent influenza inactivated vaccine (IIV3) boost. Contemp. Clin. Trials 44, 112–118 (2015).

  224. 224.

    Ledgerwood, J. E. et al. Prime-boost interval matters: a randomized phase 1 study to identify the minimum interval necessary to observe the H5 DNA influenza vaccine priming effect. J. Infect. Dis. 208, 418–422 (2013).

  225. 225.

    Bahl, K. et al. Preclinical and clinical demonstration of immunogenicity by mRNA vaccines against H10N8 and H7N9 influenza viruses. Mol. Ther. 25, 1316–1327 (2017).

  226. 226.

    Feldman, R. A. et al. mRNA vaccines against H10N8 and H7N9 influenza viruses of pandemic potential are immunogenic and well tolerated in healthy adults in phase 1 randomized clinical trials. Vaccine 37, 3326–3334 (2019).

  227. 227.

    Gurwith, M. et al. Safety and immunogenicity of an oral, replicating adenovirus serotype 4 vector vaccine for H5N1 influenza: a randomised, double-blind, placebo-controlled, phase 1 study. Lancet Infect. Dis. 13, 238–250 (2013).

  228. 228.

    Matsuda, K. et al. Prolonged evolution of the memory B cell response induced by a replicating adenovirus-influenza H5 vaccine. Sci. Immunol. 4, eaau2710 (2019).

  229. 229.

    Radin, J. M. et al. Dramatic decline of respiratory illness among US military recruits after the renewed use of adenovirus vaccines. Clin. Infect. Dis. 59, 962–968 (2014).

  230. 230.

    Peters, W. et al. Oral administration of an adenovirus vector encoding both an avian influenza A hemagglutinin and a TLR3 ligand induces antigen specific granzyme B and IFN-γ T cell responses in humans. Vaccine 31, 1752–1758 (2013).

  231. 231.

    Coughlan, L. et al. Heterologous two-dose vaccination with simian adenovirus and poxvirus vectors elicits long-lasting cellular immunity to influenza virus A in healthy adults. EBioMedicine 29, 146–154 (2018).

  232. 232.

    Mullin, J. et al. Activation of cross-reactive mucosal T and B cell responses in human nasopharynx-associated lymphoid tissue in vitro by modified vaccinia Ankara-vectored influenza vaccines. Vaccine 34, 1688–1695 (2016).

  233. 233.

    de Vries, R. D. et al. Induction of cross-clade antibody and T-cell responses by a modified vaccinia virus Ankara-based influenza A(H5N1) vaccine in a randomized phase 1/2a clinical trial. J. Infect. Dis. 218, 614–623 (2018).

  234. 234.

    Folegatti, P. M. et al. Safety and immunogenicity of the heterosubtypic influenza A vaccine MVA-NP + M1 manufactured on the AGE1.CR.pIX avian cell line. Vaccines (Basel) 7, 33 (2019).

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Acknowledgements

The authors thank Jeffrey C. Boyington (Vaccine Research Center, National Institute of Allergy and Infectious Disease, National Institutes of Health) for generating the HA structural model and Stefan Köester (Sanofi) for the HA and NA phylogenetic trees and the NA model. They also thank Brian DelGiudice (Sanofi) for assistance in manuscript preparation.

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Correspondence to Gary J. Nabel.

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Competing interests

C.-J.W., J.S., and G.J.N. are employees and stock owners of Sanofi, whose subsidiary Sanofi-Pasteur is a major influenza vaccine producer and has issued patents and pending filed patent applications on various influenza vaccine technologies. C.-J.W and G.J.N. are inventors of gene-based and nanoparticle-based influenza vaccines that have been filed by either Sanofi or the US government. J.R.M. and B.S.G. are employees of the US government, which has issued patents and filed patent applications on various vaccines including ferritin nanoparticle-based influenza vaccines mentioned in this article. The other authors declare no competing interests.

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CDC: Past seasons vaccine effectiveness estimates: https://www.cdc.gov/flu/vaccines-work/past-seasons-estimates.html

CDC: United States influenza vaccines 2019–2020: https://www.cdc.gov/flu/professionals/vaccines.htm

European Centre for Disease Prevention and Control: Seasonal Influenza Vaccines: https://ecdc.europa.eu/en/seasonal-influenza/prevention-and-control/vaccines/types-of-seasonal-influenza-vaccine

WHO: Influenza vaccine viruses and reagents: https://www.who.int/influenza/vaccines/virus/en/

Glossary

Influenza

A contagious respiratory disease caused by influenza viruses.

Haemagglutinin

(HA). A homotrimeric glycoprotein found on the surface of influenza virus particles responsible for the recognition of the host target cell through the binding of sialic acid-containing receptors.

Neuraminidase

(NA). A homotetrameric glycoprotein found on the surface of influenza virus particles that facilitates the virus’ release from the host cell.

Matrix protein 2

(M2). A homotetrameric protein that serves as a proton-selective channel essential for maintaining a pH gradient across the viral membrane during host cell entry and is vital for virus replication.

Nucleoprotein

(NP). A viral structural protein that encapsidates negative-strand viral RNA to allow RNA transcription, replication and packaging.

Haemagglutination inhibition

(HAI). The haemagglutination inhibition assay is a method to quantify the relative titre of viruses or determine the concentration of antiserum or antibody required to prevent haemagglutination, a process in which influenza viruses bind and agglutinate red blood cells in cell culture.

Virus-like particle

A molecule that closely resembles viruses but lacks certain viral genetic materials to be infectious.

Vaccine adjuvant

An immunostimulant used with an antigen to improve its immunogenicity.

Pandemic influenza

An epidemic caused by worldwide spread of a new influenza virus that infects a large portion of the population globally.

Toll-like receptor

A family of type I transmembrane pattern recognition receptors that sense foreign pathogens or endogenous danger signals and play a central role in early innate immune response.

Antibody-dependent cellular cytotoxicity

An adaptive immune response by which specific antibodies bind to foreign antigens and, in turn, recruit effector cells to lyse target cells.

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Wei, C., Crank, M.C., Shiver, J. et al. Next-generation influenza vaccines: opportunities and challenges. Nat Rev Drug Discov (2020). https://doi.org/10.1038/s41573-019-0056-x

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