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

Abstract

Background: 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