live attenuated influenza vaccine (AstraZeneca)

Live Attenuated Influenza Vaccine (LAIV) is an intranasal vaccine containing live but weakened influenza viruses. It is administered as a nasal spray and is designed to mimic natural infection to induce a broad immune response, including mucosal IgA, serum IgG, and T-cell mediated immunity. The vaccine uses a cold-adapted, temperature-sensitive master donor virus (MDV) backbone, typically derived from the A/Ann Arbor/6/1960 strain, which limits replication to the cooler temperatures of the nasopharynx (approx. 32°C) and prevents replication in the warmer lower respiratory tract (37°C). The quadrivalent formulation (LAIV4) contains four strains: two influenza A (H1N1 and H3N2) and two influenza B (Victoria and Yamagata lineages). It is indicated for the prevention of seasonal influenza in healthy individuals aged 2 through 49 years.

Brand names

FluMistFluMist QuadrivalentFluenzFluenz Tetra

Other names

Nasal spray flu vaccineCold-adapted influenza vaccineinfluenza vaccine (live, attenuated)