influenza vaccine (recombinant), quadrivalent

Quadrivalent RIV (Recombinant Influenza Vaccine) is a vaccine formulation containing four recombinant hemagglutinin (HA) proteins, typically representing two Influenza A strains (H1N1 and H3N2) and two Influenza B lineages (Victoria and Yamagata). Developed by Sanofi (following the acquisition of Protein Sciences), the most prominent version is marketed as Flublok Quadrivalent. Unlike traditional egg-based vaccines, RIV is produced using a baculovirus expression system in insect cells (Sf9 cells), which eliminates the risk of egg-adaptive mutations and allows for a higher antigen concentration (45 mcg per strain compared to 15 mcg in standard vaccines). Clinical development continues for optimized formulations, including those with different H3 antigens or the addition of adjuvants to enhance immunogenicity, particularly in older adults.

Brand names

Flublok Quadrivalent

Other names

quadrivalent recombinant influenza vaccinerecombinant influenza vaccine, quadrivalent