Background. A two dose measles vaccination schedule is recommended routinely for all schoolentry-aged children. We evaluated this recommendation by determining both measles antibody seroprevalence and the response to revaccination in seronegative children in this age group.
Methods. Children 4 to 6 years of age who had received a single dose of measles vaccine between the ages of 15 to 17 months were tested for measles antibody by using an enzyme-linked immunosorbent assay (ELISA) microneutralization technique. Seronegative children were revaccinated and again tested for measles antibody (immunoglobulin M [IgM] and neutralizing).
Results. Of 679 children tested, 37 (5.4%) were seronegative. Seronegativity was not significantly associated with age, sex, race, age at initial vaccination, time since vaccinalion, or maternal year of birth. However, children of mothers with a college degree were 12 times more likely to be seronegative than children of mothers who never attended college (P< .01). Of the 37 seronegative children, 36 seroconverted after revaccination—33 producing IgM measles antibody, suggestive of a primary immune response. The cost per seroconversion would have been an estimated $415 if all 679 children had been revaccinated.
Conclusions. Revaccination reduces the pool of children who are susceptible to measles. Although the cost per seroconversion is high, a two-dose schedule should reduce the substantial costs of controlling measles outbreaks by reducing the number of outbreaks.