Immunological effectiveness of a booster inoculation against measles in children remaining seronegative after vaccination

Booster immunization against measles with a highly immunogenic vaccine leads to the development of prolonged postvaccinal immunity lasting at least 6-7 years (the term of observation) in the groups of children found to be seronegative after the titration of their blood sera with 1 hemagglutinating unit (HAU) of the antigen. The booster immunization of children in whose blood sera the minimal concentrations of antibodies can be determined in the presence of 1 HAU of the antigen (seronegative in the presence of 4 HAU) is less effective. The serological checks of immunized children entering preschool institutions and the primary grades at schools and the subsequent booster immunization of children found to be seronegative will lead to a further decrease in measles morbidity.