XK and influenza: The RNA of the vaccine virus includes: segments 1, 2, 3, 5, 8; segment 7 lacking the entire BM2 open reading frame (ORF) from influenza B/Lee/1940; and the HA and NA vRNA (segments 4, 6) from influenza B/Brisbane/60/2008 (B/Bris60, BVic lineage) or B/Wisconsin/01/2010 (B/WI01, BYam lineage).