Immunization coverage and its relationship to preventive health care visits among inner-city children in Baltimore

Objective. To provide empirical data on immunization coverage and the receipt of preventive health care to inform policy makers' efforts to improve childhood immunization. Design and methods. We surveyed a random sample drawn from a birth cohort of 557 2-year-old children living in the inner-city of Baltimore. Complete information on all their preventive health care visits and immunization status was obtained from medical record audits of their health care providers. Main outcome measures. Age-appropriate immunizations and preventive health care visits. Results. By 3 months of age, nearly 80% made an age-appropriate preventive health visit, but by 7 months of age, less than 40% had a preventive visit that was age-appropriate. In the second year of life, 75% made a preventive health visit between their 12- and 17-month birthdays. The corresponding age-appropriate immunization levels were 71% for DTP1, 39% for DTP3, and 53% for measles-mumps-rubella vaccine. Infants who received their DTP1 on-time were twice as likely to be up-to-date by 24 months of age. Conclusions. Our analyses focus attention on the performance of the primary health care system, especially during the first 6 months of life. Many young infants are underimmunized despite having age-appropriate preventive visits, health insurance coverage through Medicaid, and providers who receive free vaccine from public agencies. Measles vaccination coverage could be improved by initiating measles-mumps-rubella vaccine vaccination, routinely, at 12 months among high risk populations.