Influenza A/Subtype and B/Lineage Effectiveness Estimates for the 2011–2012 Trivalent Vaccine: Cross-Season and Cross-Lineage Protection With Unchanged Vaccine

Abstract

Phenotypic and genotypic characterization of circulating and vaccine viruses enhances understanding of TIV performance, shown in 2011-2012 to be substantial against well-conserved A(H1N1)pdm09 and lineage-matched influenza B, suboptimal against genetic-variants of A/H3N2, and further reduced against lineage-mismatched influenza B. With unchanged vaccine components, protection may extend beyond a single season.