Persistence of rubella antibodies after vaccination: detection after experimental challenge.

Radioimmunoassay (RIA) and single radial hemolysis (SRH) were used to measure the persistence of rubella antibodies in 123 women who had received one of four rubella vaccines (Cendehill, HPV-77 DE-5, RA27/3, and To-336) six to 16 years earlier. Only two (1.6%) vaccinees had no antibodies detectable by RIA, although 19 (15.4%) had very low levels (less than 15 IU/ml) detectable by SRH. Rubella-specific IgA persisted in sera for seven to nine years in the majority of 43 vaccinees from whom serial samples were obtained, and rubella-specific nasopharyngeal IgA could be detected up to two years after natural infection and vaccination in all vaccinees. Rubella-specific serum IgM responses were detected in 41 of 43 vaccinees and persisted at low levels for up to three years in seven of them, four of whom had received HPV-77 DE-5 vaccine. After 31 volunteers with antibody levels of less than 15 IU were challenged intranasally with RA27/3, viremia was detected in one, a girl who had a history of vaccination at school.