influenza virus vaccine, trivalent

**Influenza virus vaccine, trivalent** is a vaccine formulation designed to protect against three influenza virus strains: one influenza A(H1N1) virus, one influenza A(H3N2) virus, and one influenza B (Victoria lineage) virus. It is administered annually and is indicated for the prevention of influenza illness in individuals 6 months of age and older, depending on the specific vaccine product and regulatory approvals[1][3][4]. For the 2025-2026 U.S. season, all approved influenza vaccines are trivalent following the removal of the B/Yamagata lineage component due to its absence in global surveillance[2][3]. Several formulations are available, including inactivated (IIV3), recombinant (RIV3), and live attenuated (LAIV3) vaccines. The mechanism of action is based on stimulating active immunity, inducing the production of neutralizing antibodies against viral hemagglutinin antigens, which helps prevent infection or reduce severity if infection occurs. Primary manufacturers include CSL Seqirus, Sanofi, GSK, and Protein Sciences (now Sanofi)[1][4]. The vaccines are widely recommended by CDC, ACIP, and FDA. For older adults, enhanced formulations such as high-dose, adjuvanted, or recombinant trivalent vaccines are preferentially recommended[1][4].

Brand names

AfluriaFluarixFlucelvaxFluzoneFlublokAgrifluFluMistFluad

Other names

trivalent influenza vaccinetrivalent flu vaccineIIV3IIV-3IIV 3RIV3RIV-3RIV 3LAIV3LAIV-3LAIV 3trivalent inactivated influenza vaccinetrivalent recombinant influenza vaccinetrivalent live attenuated influenza vaccine