influenza vaccine (split virion, inactivated), quadrivalent

The **influenza vaccine, quadrivalent, inactivated, split-virus** is a biologic vaccine used for active immunization against seasonal influenza. It is a split-virion preparation, meaning the virus has been disrupted by detergents to reduce reactogenicity while maintaining immunogenicity. The quadrivalent formulation typically contains hemagglutinin (HA) antigens from four distinct influenza virus strains: two influenza A subtypes (H1N1 and H3N2) and two influenza B lineages (Victoria and Yamagata). By including both circulating B lineages, it provides broader protection than trivalent vaccines, which only cover one B strain. The vaccine works by stimulating the immune system to produce neutralizing antibodies against the viral hemagglutinin, thereby preventing the virus from attaching to and entering host cells. It is typically administered as a single intramuscular injection for each flu season.

Brand names

Fluarix TetraAlpharix Tetraalfa-Rix TetraVaxigripTetraFluQuadriAfluria Quadrivalent

Other names

quadrivalent inactivated influenza vaccineQIVIIV4IIV-4IIV 4split-virion inactivated influenza vaccine