Safety and Immunogenicity of an Inactivated Quadrivalent Influenza Vaccine in Children 6 Months through 8 Years of Age

BACKGROUND:Strains of 2 distinct influenza B lineages (Victoria and Yamagata) have cocirculated in the United States for over a decade, but trivalent influenza vaccines (TIVs) contain only 1 B-lineage strain. Each season, some or most influenza B disease is caused by the B lineage not represented in that season’s TIV. Quadrivalent influenza vaccines (QIVs) containing a strain from each B lineage should resolve this problem. METHODS:This was a Phase III, randomized, multicenter trial in the United States among children 6 months to