Assessment of Immunization Compliance Among Children in the Department of Defense Health Care System

Abstract

Objective. To describe immunization rates among children enrolled in the Department of Defense health care system and to determine risk factors for delay. Design. Cross-sectional survey of immunization records and demographic characteristics among parents of children presenting for acute care at seven pediatric clinics operated by the Department of Defense. Participants. Subjects were 1977 children aged 2 months to 18 years. Outcome Measures. Immunization rates were measured for various age strata from infancy to adolescence. Results. The overall immunization rate was 84%. By age 2 years, 86% of patients had received four diphtheriatetanus -pertussis, three oral polio, Haemophilus influenzae type b, and measles-mumps-rubella (MMR) vaccines. At school entry, 87% of children were fully immunized for diphtheria-tetanus-pertussis and MMR. However, only 50% of adolescents were up-to-date, primarily because of failure to receive booster doses of MMR. Seventy-nine percent of parents whose children were delayed thought that they were up-to-date. Factors associated with immunization delay included incorrect parental perception of immunization status, failure to keep routine health maintenance visits, and non-white race. Socioeconomic status, parental education level, access to care, and family mobility had no effect on immnization status. Conclusions. Although immunization rates for preschoolers approached national goals, accessibility to care and free vaccines did not guarantee immunization compliance, especially among adolescents. Most patients with delayed vaccinations were older children and adolescents whose school and parental reports of immunization status were incorrect. Immunization delay in our study was primarily the result of a failure to track patients and notify parents of when immunizations were due.