A phase 2/3 double blind, randomized, placebo-controlled study to evaluate the safety and immunogenicity of a seasonal trivalent inactivated split-virion influenza vaccine (IVACFLU-S) in healthy adults in Vietnam

ABSTRACTBackground: Under the WHO’s Global Action Plan for influenza vaccines, we conducted a phase 2–3 study of IVACFLU-S, a trivalent, seasonal inactivated influenza vaccine candidate.Methods: In the phase 2 portion of the study, 252 participants received one dose of 15 mcg hemagglutinin (HA) vaccine per strain or placebo. Following determination of safety, 636 additional participants were randomized in phase 3 to receive vaccine or placebo. Immunogenicity was assessed in a subset of the participants in the phase 3 study.Results: Higher proportion (70%) of participants in the IVACFLU-S arm reported solicited local adverse events (AEs) (p < .0001) as compared to placebo (25%). Mild injection site pain and tenderness were most common AEs seen in 55% and 60% of participants in the vaccine group. The solicited systemic AEs were comparable (p = .4149). The majority of solicited and unsolicited AEs were mild to moderate in severity. In the vaccine arm for the combined age group of 18–60 years of age, seroconv...