Concurrent Infection with Influenza A and B Viruses in a Single Epidemic of Influenza

Abstract

Summary Investigation of an influenza epidemic in a children’s institution disclosed concurrent infection of the population with both influenza A virus and influenza B virus. Individuals of the population were found to have been infected with influenza A virus, with influenza B virus, or with both viruses. The availability of pre-epidemic sera from the entire population made it possible to determine the actual incidence of inapparent infection during an influenza outbreak; clinically inapparent infections occurred in 8% of the population. Collateral studies with hamsters established that a mammalian host may be simultaneously infected with influenza A and B viruses and develop antibodies against both viruses, although the degree of antibody response may be less than that resulting from infection with either virus alone.