Leveraging state immunization information systems to measure the effectiveness of rotavirus vaccine.

OBJECTIVE: Electronic immunization information systems (IISs) are now established in almost all US states. We used the IIS in Minnesota- Georgia- and Connecticut for immunization data and as the source of 1 of 2 control groups to measure pentavalent rotavirus vaccine (RV5) effectiveness (VE) using case-control methodology. PATIENTS AND METHODS: Case-subjects were vaccine-eligible children who presented to 1 of 5 hospitals or emergency departments with gastroenteritis and had rotavirus antigen detected in stool during any of 3 rotavirus seasons (2007-2009). Two control groups were used: children with gastroenteritis who tested negative for rotavirus and children from the IIS matched by zip code and birth date. In Minnesota and Georgia- immunization records for rotavirus-positive and -negative children were also obtained from providers. RESULTS: Overall- 402 (96%) rotavirus case-subjects and 825 (97%) rotavirus-negative controls who met eligibility criteria were found in the IISs. Ten IIS controls were identifi