Rapid Cycle Analysis of Pentavalent Rotavirus (RotaTeq®) Vaccine Safety in the Vaccine Safety Datalink (VSD) Population: Interim Results

Learning Objectives for this Presentation:
By the end of the presentation, participants will be apprised of the interim results of a VSD RotaTeq safety evaluation.

Background:
A previously licensed rotavirus vaccine was associated with an increased risk of intussusception. In February 2006, a pentavalent rotavirus vaccine (PRV) was licensed for use in US infants. Although large prelicensure studies of PRV found no increased risk of intussusception, postlicensure monitoring is needed for this and other serious adverse events (AEs).

Objectives:
Compare observed and expected cases of intussusception, Kawasaki syndrome, and other pre-specified AEs during a 30 day window after PRV receipt in the VSD population.

Methods:
AEs following PRV are identified weekly based on ICD-9 diagnoses codes occurring in inpatient, outpatient, and emergency department files. Observed numbers of AEs in PRV recipients are compared with expected numbers, which are derived from historical or concurrent comparison groups. Historical intussusception incidence in VSD (1991-2004) is used to estimate the expected number of intussusception cases in PRV recipients by week of age. Statistical analyses are conducted using maximized sequential probability ratio testing (maxSPRT), which adjusts for repeated testing until a predetermined number of expected cases are reached. Cases of intussusception are validated by medical record review.

Results:
Between 05/21/2006 and 11/03/2007, 121,566 doses of RotaTeq were administered in the VSD population. Four infants received ICD-9 codes for intussusception after PRV administration; one case has been validated and three are under review. Two cases occurred following the first dose of PRV; two occurred after the second dose. All cases occurred in infants given the vaccine within the recommended age range. Based on historical background incidence, 3.8 cases were expected. No confirmed signals have been generated for any AEs following PRV.

Conclusions:
Interim results provide no evidence that PRV receipt is associated with an increased risk for intussusception or other pre-specified adverse events.