Enhancing Vaccine Safety Surveillance: A capture-recapture analysis of intussusception after rotavirus vaccination

The Vaccine Adverse Event Reporting System (VAERS) is the passive reporting system for postmarketing surveillance of vaccine safety in the United Stat es. The proportion of cases of an adverse event after vaccination that are reported to VAERS (i.e., VAERS reporting completeness) is mostly unknown. T herefore, the risk of such an event cannot be derived from VAERS only. To s tudy whether its reporting sensitivity and risks could be estimated, VAERS was linked to data from a case-control and a retrospective cohort study in a capture-recapture analysis of intussusception after rotavirus vaccination (RV). Cases of intussusception after RV were selected from the common time frame (December 1998 through June 1999) and the common geographic area (19 states) of the three sources. Matching occurred on birth date, gender, sta te, date of vaccination, and date of diagnosis. Thirty-five matches were id entified among a total of 84 cases. The estimated VAERS reporting completen ess was 47%. The relative risks of intussusception in the periods 3-7 and 8 -14 days after RV (relative risk = 22.7 and 4.4, respectively) were compara ble with those reported in the two studies. Linkage of VAERS to complimenta ry data sources may permit more timely postmarketing assessment of vaccine safety.