influenza vaccine (live attenuated)

MEDI-558 is a trivalent live attenuated influenza vaccine (LAIV) developed by MedImmune (a subsidiary of AstraZeneca). Administered intranasally, it is the trivalent formulation of FluMist. The vaccine contains three live, cold-adapted, temperature-sensitive influenza virus strains: two Type A (H1N1 and H3N2) and one Type B. These strains are engineered to replicate in the cooler environment of the nasal passages but are unable to replicate in the warmer lower respiratory tract. By mimicking natural infection, MEDI-558 induces both mucosal and systemic immunity, including humoral and cell-mediated responses against the hemagglutinin and neuraminidase surface antigens. It was the first intranasal influenza vaccine approved in the United States and served as the basis for the subsequent quadrivalent formulation (MEDI3250).

Brand names

FluMist

Other names

trivalent live attenuated influenza vaccineLAIV3LAIV-3LAIV 3trivalent LAIVCAIV-T