A Study to Evaluate the Immunogenicity of Quadrivalent LAIV in Adults 18 to 49 Years of Age

This randomized, double-blind, active controlled, multicenter study enrolled 1,800 subjects who were 18 to 49 years of age. Subjects were randomized by site in a 4:1:1 fashion to receive a single dose of Q/LAIV, trivalent FluMist containing an influenza B strain from the Yamagata lineage (FluMist/B/Yamagata), or trivalent FluMist containing an influenza B strain from the Victoria lineage (FluMist/B/Victoria). The study was conducted at multiple sites in the USA in the influenza off-season.