Flu B 2025. Learn about the switch from quadrivalent (four. Trivalent flu vaccines are formulated to protect against three main groups of circulating seasonal influenza type a and b viruses, an a(hin1) virus, an a(h3n2) virus, and a b/victoria lineage virus.
Trivalent flu vaccines are formulated to protect against three main groups of circulating seasonal influenza type a and b viruses, an a(hin1) virus, an a(h3n2) virus, and a b/victoria lineage virus. Therefore, inclusion of a b/yamagata antigen component of influenza vaccine is no longer warranted.
