Use of the state immunization information system to assess rotavirus vaccine effectiveness in Connecticut, 2006–2008

Abstract

Immunization information systems (IIS) contain individual vaccination records and have potential use for evaluating post-licensure vaccine effectiveness (VE). A matched case–control study was performed by using the Connecticut state IIS to calculate rotavirus VE against hospitalization; results were compared with pre-licensure efficacy and with estimates previously obtained by traditional case–control methods using matched controls from medical sources and medical chart abstracted data. Case–patients (n=54) were vaccine-eligible children with IIS entry and hospitalized for rotavirus gastroenteritis during July 2006–December 2008; each was matched to five control subjects (n=270) who were randomly selected from IIS based on case-patient's birth date and town of residence. VE of at least one dose was 90.6%, comparable to the pre-licensure efficacy of 96% and to the unadjusted 83.5–90.7% estimates by using traditional case–control methods. IIS can be a convenient and potentially accurate tool for calculating VE.