Absence of cell-mediated immunity to rubella virus 5 years after rubella vaccination.

The long-term effectiveness of rubella vaccination in childhood is particularly important because the ultimate goal of immunization is the prevention of infection during pregnancy. Of 25 healthy children tested 4 to 5 years after rubella vaccination, 19 showed no evidence of cell-mediated immunity (CM) to rubella virus despite the presence of hemagglutination-inhibition or complement-fixation antibodies or both. Twenty-two of 25 seropositive, naturally infected young adults showed evidence of CMI. These results indicate that fetuses of women who have been vaccinated against rubella may not be protected against damage by wild rubella infection during the pregnancy, when CMI is physiologically depressed.