Flu Strains 2024. Candidate vaccine strains and potency reagents: Human infection with an influenza (flu) virus that normally spreads in pigs and not people.

Trivalent flu vaccines are formulated to protect against three flu viruses (an a (h1n1) virus, an a (h3n2) virus, and a b/victoria virus). Influenza virus strains for a trivalent vaccine composition for use in the u.s.