Use of an immunization information system to assess the effectiveness of pentavalent rotavirus vaccine in US children

Immunization information systems (IISs) are accessible sources of immunization data. We validated immunization information from a local IIS against provider records and assessed the system's utility in evaluating vaccine effectiveness against rotavirus disease using a case-control study. Among the 91% of case and control patients with immunization records, 49% were in the IIS, and 97% had a provider record. Good agreement was observed across record sources (к = 0.65). Vaccine effectiveness (VE) was 82% using IIS data compared to 82–88% using provider data. Controls identified through the IIS provided VE estimates similar to hospital control patients. IISs could represent a valuable source of data for effectiveness evaluations.