Safety assessment and immunogenicity of a cell-culture-derived influenza vaccine in adults and elderly subjects over three successive influenza seasons

Background Adult and elderly subjects previously immunized with cell culture-derived (CCIV; Optaflu®) or egg-derived (TIV; Agrippal®) trivalent influenza vaccines were enrolled in two extension studies (E1 and E2) to evaluate safety and immunogenicity after revaccination with CCIV/TIV alone or in combination with concomitant pneumococcal vaccine (PV).Methods Adults and elderly subjects (n = 2609) were randomized 1:1 in E1 and allocated 3:1 in E2 to receive CCIV/TIV. In E2, a subset of elderly subjects was randomized to receive CCIV/TIV, with or without PV. Adverse reactions were monitored for six months and immunogenicity was assessed by hemagglutination inhibition (HI) assay using CHMP criteria.Results Overall, the safety profile of both vaccines was similar, no serious adverse events related to either vaccine occurred. Mild or moderate pain was the most commonly reported reaction. Reactogenicity was slightly higher in elderly subjects receiving CCIV/TIV concomitantly with PV [46% vs. 37%; p = non-signif...