Measuring immunization coverage.

OBJECTIVE: Information about immunization coverage comes from five major sources: the National Immunization Survey- the National Health Interview Survey- retrospective school-entry surveys- the Health Plan Employer Data and Information Set (HEDIS) measures reported by managed care plans- and assessments performed on clinics and private practices. In this article- we describe the methodology of the major surveys- discuss technical and policy issues in measuring immunization coverage- and identify issues that must be addressed to harmonize immunization rates calculated from different sources. METHODS AND TOPICS: We describe the (1) design and methodology of the five major sources of immunization coverage assessments- (2) issues and controversies in measuring immunization coverage- and (3) preliminary efforts to harmonize calculation of immunization coverage. Technical and policy issues involve dose and interval requirements- which vaccines are included in the series-completion calculations- and who is excluded