Abstract

Sera were collected from 292 army recruits before and after a rubella outbreak in winter 1971. Of the 37 initially susceptible men, 34 (92%) had serologic evidence of rubella infection, but only 6 (16%) had a rash. A 4-fold or greater booster response in rubella hemagglutination-inhibiting (HI) antibodies was found in 15 (5.9%) of the initially immune men. Paired sera from the booster cases were also titrated by complement fixation (CF) using purified rubella virions (V) and virus-free rubella soluble (S) antigen preparation as antigens, and also by platelet aggregation (PA) using rubella S antigen. In 8 cases reinfection was evident by all serologic techniques, in the others the antibody responses to rubella S antigen were weak or absent.