Correlations between measles, mumps, and rubella serum antibody levels in Olmsted County school children.

We examined correlations between serum antibody levels to determine whether individuals with low levels of antibody to one component of the measles, mumps, and rubella (MMR) vaccine were also likely to have low antibody levels to the other MMR vaccine components. Our results indicate that children who had a low antibody level to one component of the MMR vaccine had a modest probability of having a low antibody level to either of the other MMR vaccine components. Overall, we found small, but statistically significant, correlations between antibody levels that were largely unaffected by race, sex, age at immunization, and time since immunization. While the correlations we observed were modest, approximately 25% of our population was seronegative for at least one component of the MMR vaccine. Therefore, our results support the current policy of continuing to administer the trivalent MMR vaccine even when only a single low antibody titer is observed.