Influenza Vaccine Strains
ANTIGENS Seasonal flu is a common infectious disease of the respiratory tract caused by influenza virus. There are four types of influenza virus, influenza type A, B, C, and D. The A and B types are of most interest to the medical community because they are the culprits for seasonal epidemics. Occasionally, influenza A, like the A/California/04/09 (H1N1) and A/Hong Kong/1/1968 (H3N2), can even cause global pandemics.