Measles in schools: age at vaccination vs risk of disease

In January and February 1983, ten students in three schools in Batesville, AR developed measles. The index case was in a 7-year-old unvaccinated student who had just returned from a trip to Florida. Risk of measles for inadequately immunized students (unimmunized or immunized before their first birthday) in schools was 22 times greater than for those who had been immunized on or after 12 months of age. Measles transmission occurred despite 90% of the school children having had documented evidence of adequate vaccination.