Immunization registries in the United States: implications for the practice of public health in a changing health care system.

Although immunization rates among children are rising across the country, rates in inner-city areas have remained at approximately 50%-60%, < or = 30% lower than corresponding suburban or state immunization levels. The failure to raise immunization levels in poor, underserved populations is caused in part by the lack of timely and accurate child-specific immunization information for providers and parents. Immunization registries are a new tool in health care that can be used to address these and other barriers to effective immunization delivery. Moreover, immunization registries have the potential to help health care officials track and improve delivery for a broad range of important child health services. An immunization registry is a computerized database of information on children (usually preschool-age children) in a defined population (e.g. those enrolled in a health maintenance organization or living in a specific geographic area), which is used to record and track all immunizations received by each child. The registry receives the information primarily from public and private providers that administer immunizations, as well as from parents, schools, and other agencies. A fully functioning immunization registry can be used to identify individual children in need of immunizations and to report on immunization rates by population characteristics such as child age, assigned provider, or geographic area (e.g. neighborhood, city). Today, > 250 local public health departments have immunization registries that are in various stages of planning or development. Only a small number of these registries meet the minimum functional criteria of maintaining records on 95% of all eligible 2-year-old children in the target population and providing an electronic immunization record that is accessible to providers. Nascent immunization registries represent innovative technologic solutions to the challenge of monitoring health problems and health care access on a population basis. This is a fundamental activity of public health agencies, but one that is increasingly shared by large health maintenance organizations. The study of the development of immunization registries across the United States provides an important case study for how public health agencies will use the rapidly developing health information infrastructure to perform health assessment and health assurance activities in a managed care environment.