Immunity against measles and rubella in Massachusetts schoolchildren.

A statewide serosurvey was conducted among 6th, 10th and 12th grade Massachusetts schoolchildren in 1982. Sera were screened using a standard measles hemagglutination inhibition (HI) assay, a sensitive measles plaque neutralization assay, and four rubella assays with corresponding sensitivity limits of approximately 15, 10, 7.5, and 5 international units (IU) of rubella antibody/ml respectively. Using the most sensitive assays, seroprevalence was 98.6% for measles antibodies and 93.1% for any rubella antibodies. For persons who received single doses of either combined measles and rubella vaccines or separate single vaccinations at different times, there were no significant differences in seroprevalence using sensitive assays. Of persons who received combined vaccines, 99.3% had antibody against measles compared to 98.4% of single antigen recipients. For rubella, 98.6% of combined vaccine recipients had antibody compared to 95.7% of single antigen recipients. These seroprevalence data indicate the effectiveness of a combined vaccination program and support epidemiologic data indicating virtual elimination of these diseases in Massachusetts schoolchildren.