Immunogenicity of AS03-adjuvanted and non-adjuvanted trivalent inactivated influenza vaccines in elderly adults: A Phase 3, randomized trial and post-hoc correlate of protection analysis

• Published in: Human vaccines & immunotherapeutics 2016-12, Vol.12 (12), p.3043-3055
• Main Authors: Ruiz-Palacios, Guillermo M., Leroux-Roels, Geert, Beran, Jiri, Devaster, Jeanne-Marie, Esen, Meral, Launay, Odile, McElhaney, Janet E., van Essen, Gerrit A., Benoit, Anne, Claeys, Carine, Dewé, Walthère, Durand, Christelle, Duval, Xavier, Falsey, Ann R., Feldman, Gregory, Galtier, Florence, Gervais, Pierre, Hwang, Shinn-Jang, McNeil, Shelly, Richardus, Jan Hendrik, Trofa, Andrew, Oostvogels, Lidia
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; alpha-Tocopherol - administration & dosage; Antibodies, Viral - blood; AS03; correlates of protection; Drug Combinations; Female; Geriatry and gerontology; Hemagglutination Inhibition Tests; Human health and pathology; Humans; immunogenicity; Immunology; Infectious diseases; Influenza A Virus, H3N2 Subtype - immunology; Influenza Vaccines - administration & dosage; Influenza Vaccines - immunology; Influenza, Human - prevention & control; Influenza, Human - virology; Life Sciences; Male; older; Polysorbates - administration & dosage; Research Papers; Santé publique et épidémiologie; seasonal influenza; Single-Blind Method; Squalene - administration & dosage; Treatment Outcome; vaccine; Vaccines, Inactivated - administration & dosage; Vaccines, Inactivated - immunology; Vaccinology
• ISSN: 2164-5515; 2164-554X
• DOI: 10.1080/21645515.2016.1219809

In this study we describe the immunogenicity results from a subset of older people (N = 5187) who participated in a Phase 3 randomized, observer-blinded trial of AS03-TIV versus TIV (Fluarix™) (ClinicalTrials.gov, NCT00753272). Participants received one dose of AS03-TIV or TIV in each study year and antibody titers against the vaccine strains were assessed using hemagglutination-inhibition (HI) assay at 21 d and 180 d post-vaccination in each vaccine group in the 2008/09 (Year 1) and 2009/10 (Year 2) influenza seasons. Manufacturing consistency of 3 lots of AS03-TIV for HI antibody responses in Year 1 was a co-primary objective. In a post-hoc analysis, a statistical regression model included 4830 subjects in whom immunogenicity and laboratory-confirmed attack rate data were available; the analysis was performed to assess HI antibody titers against A/H3N2 as a correlate of protection for laboratory-confirmed A/H3N2 influenza. AS03-TIV and TIV elicited strong HI antibody responses against each vaccine strain 21 d post-vaccination in both years. The manufacturing consistency of 3 lots of AS03-TIV was demonstrated. In both years and each vaccine group, HI antibody responses were lower for A/H1N1 than the other vaccine strains. Day 180 seroconversion rates (proportion with ≥4-fold increase in titer compared with pre-vaccination titer) in Year 1 in the AS03-TIV and TIV groups, respectively, were 87.7% and 74.1% for A/H3N2, 69.7% and 59.6% for influenza B, and 58.3% and 47.4% for A/H1N1. The post-hoc statistical model based on A/H3N2 attack rates and HI antibody titers estimated that a 4-fold increase in post-vaccination titers against A/H3N2 was associated with a 2-fold decrease in the odds of A/H3N2 infection.