Reactogenicity to primary and repeated vaccination with influenza split virus vaccine.

Influenza vaccines (split, adsorbed, low nitrogen) of two different antigen concentrations (commercial production) were administered to 1,111 adult persons of both sexes. Up to five previous vaccinations had been given to the population under observation. Their reactions both local and general were not different in primo-vaccinees or boostered persons. Increasing numbers of previous vaccinations were not reflected by increasing rates of complaints. Disregarding immunization history, the group given the higher concentrated vaccine showed a lower rate of side effects while the lower antigen concentration produced a higher rate. The relevance of the observation that no sensitizing effect occurred in persons with up to five vaccinations may be a characteristic of split adsorbed influenza vaccines of high purity.