Measles immunization coverage determined by serology and immunization record from children in two Chicago communities

Objectives. We compared the prevalence of measles immunization determined by serology with the prevalence of measles immunization determined by immunization records, and identified factors predictive of measles immunization among a sample of children from two Chicago communities. Methods. We collected demographic information and blood specimens from a sample of children aged 12-71 months in two Chicago communities at risk for low measles immunization coverage levels. We collected immunization information from provider records, parent-held records, and the statewide immunization registry. We compared evidence of immunization determined by serology with evidence of immunization from these three sources of immunization records. Results. The sample of children from the two communities had serologic measles immunity levels of 85% and 90%. Significantly fewer children had evidence of immunization by record in both communities (45% and 63%, respectively). Conclusions. Immunization coverage levels determined using immunization records were significantly lower than immunization coverage determined using serology. A fully populated immunization registry used by all immunization providers could prevent the problems of record loss and scatter.