Immunogenicity of aIIV3, MF59-adjuvanted seasonal trivalent influenza vaccine, in older adults ≥65 years of age: Meta-analysis of cumulative clinical experience

Abstract

ObjectiveCompare the immunogenicity of MF59-adjuvanted trivalent inactivated influenza vaccine (aIIV3; Fluad™) versus conventional trivalent inactivated influenza vaccine (IIV3) in an integrated dataset using a meta-analysis. MethodsIn a meta-analysis, the immunogenicity of aIIV3 in subjects ≥65 years of age was compared with IIV3 immunogenicity using hemagglutination inhibition assay results from 23 phase I through III randomized controlled trials, including 16 first-dose vaccination studies and 7 revaccination studies assessing immunogenicity after second or third annual vaccination. ResultsThe full analysis set consisted of 11,105 subjects (5869 aIIV3 and 5236 IIV3). In the revaccination studies, 822 individuals received 2 consecutive annual influenza vaccinations (492 aIIV3 and 330 IIV3), and 237 received 3 (150 aIIV3 and 87 IIV3). Overall, across all strains, the meta-analyzed point estimates for seroconversion (SC) and geometric mean titer (GMT) ratio were significantly higher for aIIV3 versus IIV3. The meta-analyzed percent differences in SC with corresponding 95% confidence intervals (CI) for A/H1N1, A/H3N2, and B strain were 9.5% (5.2–13.9), 10.5% (6.6–14.5), and 12.7% (8.6–16.8), respectively. The meta-analyzed GMT ratios with corresponding 95% CI for A/H1N1, A/H3N2, and B strain were 1.15 (1.01–1.31), 1.30 (1.18–1.44), 1.23 (1.15–1.31). Antibody responses against heterologous influenza strains were also significantly higher with aIIV3. Revaccination studies showed continued robust immune response to aIIV3 with repeated vaccination. ConclusionsaIIV3 elicited a statistically significantly greater immune response compared to conventional IIV3 in older adults, increasing the breadth and duration of the immune response.