Assessing immunization registry data completeness in Bexar County, Texas

Background: Immunization information systems (or registries) are increasingly being used to promote and sustain high levels of vaccination coverage. However, the perception among many providers that registry data are too incomplete to be relied on when making immunization decisions has impeded the acceptance of registries. Methods: To evaluate registry completeness, immunization coverage levels from the San Antonio Immunization Registry System (SAIRS) were compared with coverage levels derived from immunization records from 77 (37%) of the 210 clinics participating in the Vaccines for Children (VFC) program in 1998, 44 (21%) clinics in 1999, and 10 (5%) clinics in 2000. Results: Clinic data indicated an average immunization coverage level for the 4:3:1 series of 39.8%. The overall coverage level for these clinics based on registry data was 64.1%. Registry-coverage levels for these clinics were less than or equal to65% above the coverage levels based on clinic records. Conclusions: Immunization coverage levels based on SAIRS data were the same or higher than coverage levels based on clinic records. These data suggest that San Antonio's registry data were more complete than clinic records and may assist in changing provider perceptions regarding registry data completeness.