Measles immunization status in 1972 among first- and second-grade school children in Danbury, Connecticut

An increased incidence of rubeola among first-grade Danbury school children in 1973 led to a study of seroimmunity to rubeola in a random sample of 60% of the first- and second-grade school children (299) from whom blood samples had been obtained in October 1972 during a voluntary meningococcal vaccination program. Immunization histories derived from physicians' statements on school entry were obtained from school health department records and included date of immunization. Seventy-five percent of the study group had received measles vaccine. Of those immunized prior to 11 months of age only half had an hemagglutinating inhibiting titer (HAI) of greater than or equal to 5 five to seven years later. This antibody level correlates with immunity. Eighty-five to ninety percent of those immunized during or after the 11th month had an antibody titer of greater than or equal to 5. Seventy-one percent of those never immunized also had an HAI titer of greater than or equal to 5 indicating natural infection had occurred. As a result of this investigation, a community-wide program was initiated to vaccinate those who were more than 1 year old as well as reimmunize those who had been vaccinated before the 11th month in accord with current U.S. Public Health Service recommendations for measles immunization.