influenza vaccine live, intranasal, trivalent

FluMist Trivalent is a live attenuated, cold-adapted intranasal influenza vaccine (LAIV3) developed by MedImmune (a subsidiary of AstraZeneca). It was the first intranasal influenza vaccine licensed in the United States, receiving FDA approval in 2003 for the prevention of influenza caused by influenza A and B virus strains. The vaccine is composed of three live attenuated influenza virus reassortants (typically two influenza A subtypes and one influenza B lineage) that are cold-adapted to replicate efficiently in the cooler environment of the nasopharynx but not in the warmer lower respiratory tract. By mimicking a natural infection, it stimulates both mucosal (IgA) and systemic (IgG) immune responses against viral surface antigens, specifically hemagglutinin and neuraminidase. Following the recommendation for broader protection, the trivalent formulation was largely replaced by FluMist Quadrivalent (LAIV4), which includes a second influenza B strain.

Brand names

FluMist TrivalentFluMist

Other names

trivalent live attenuated influenza vaccineInfluenza Vaccine Live, Intranasal, Trivalent