Quadrivalent adjuvanted haemagglutinin nanoparticle influenza vaccine: a step towards better protection of older adults from the constantly mutating H3N2 influenza viruses

The H3N2 influenza subtype has been highly researched due to its rapid mutational variability, which allows it to escape a preexisting immune response, meaning that the effectiveness of the H3N2 vaccine component has been extremely low over the past few seasons, since the 2014–15 season. 1 Martin ET Cheng C Petrie JG et al. Low influenza vaccine effectiveness against A(H3N2)-associated hospitalizations in 2016–2017 and 2017–2018 of the hospitalized adult influenza vaccine effectiveness network (HAIVEN). J Infect Dis. 2020; 223: 2062-2071 Crossref Scopus (5) Google Scholar It is therefore not surprising that in seasons when the H3N2 virus predominates, many countries have markedly higher mortality rates than in other seasons, especially in older people, owing to their reduced immune functions. 2 Vestergaard LS Nielsen J Krause TG et al. Excess all-cause and influenza-attributable mortality in Europe, December 2016 to February 2017. Euro Surveill. 2017; 2230506 Crossref PubMed Scopus (79) Google Scholar In attempts to overcome the issue of immunosenescence in older adults, new enhanced influenza vaccines are being developed, such as high-dose vaccines or vaccines formulated with potent adjuvants. To some extent, these approaches have helped increase the breadth of antibody immune responses and to stimulate virus-specific T-cell responses, thus improving vaccine effectiveness in the older population. 3 Beran J Reynales H Poder A et al. Prevention of influenza during mismatched seasons in older adults with an MF59-adjuvanted quadrivalent influenza vaccine: a randomised, controlled, multicentre, phase 3 efficacy study. Lancet Infect Dis. 2021; 21: 1027-1037 Summary Full Text Full Text PDF PubMed Scopus (15) Google Scholar , 4 DiazGranados CA Dunning AJ Kimmel M et al. Efficacy of high-dose versus standard-dose influenza vaccine in older adults. N Engl J Med. 2014; 371: 635-645 Crossref PubMed Scopus (495) Google Scholar Comparison of the safety and immunogenicity of a novel Matrix-M-adjuvanted nanoparticle influenza vaccine with a quadrivalent seasonal influenza vaccine in older adults: a phase 3 randomised controlled trialqNIV was well tolerated and produced qualitatively and quantitatively enhanced humoral and cellular immune response in older adults compared with IIV4. qNIV might enhance the effectiveness of seasonal influenza vaccination, and future studies to show clinical efficacy are planned. Full-Text PDF