Risk of intussusception following administration of a pentavalent rotavirus vaccine in US infants.

CONTEXT Current rotavirus vaccines were not associated with intussusception in large prelicensure trials. However, recent postlicensure data from international settings suggest the possibility of a low-level elevated risk, primarily in the first week after the first vaccine dose. OBJECTIVE To examine the risk of intussusception following pentavalent rotavirus vaccine (RV5) in US infants. DESIGN, SETTING, AND PATIENTS This cohort study included infants 4 to 34 weeks of age, enrolled in the Vaccine Safety Datalink (VSD) who received RV5 from May 2006-February 2010. We calculated standardized incidence ratios (SIRs), relative risks (RRs), and 95% confidence intervals for the association between intussusception and RV5 by comparing the rates of intussusception in infants who had received RV5 with the rates of intussusception in infants who received other recommended vaccines without concomitant RV5 during the concurrent period and with the expected number of intussusception visits based on background rates assessed prior to US licensure of the RV5 (2001-2005). MAIN OUTCOME MEASURE Intussusception occurring in the 1- to 7-day and 1- to 30-day risk windows following RV5 vaccination. RESULTS During the study period, 786,725 total RV5 doses, which included 309,844 first doses, were administered. We did not observe a statistically significant increased risk of intussusception with RV5 for either comparison group following any dose in either the 1- to 7-day or 1- to 30-day risk window. For the 1- to 30-day window following all RV5 doses, we observed 21 cases of intussusception compared with 20.9 expected cases (SIR, 1.01; 95% CI, 0.62-1.54); following dose 1, we observed 7 cases compared with 5.7 expected cases (SIR, 1.23; 95% CI, 0.5-2.54). For the 1- to 7-day window following all RV5 doses, we observed 4 cases compared with 4.3 expected cases (SIR, 0.92; 95% CI, 0.25-2.36); for dose 1, we observed 1 case compared with 0.8 expected case (SIR, 1.21; 95% CI, 0.03-6.75). The upper 95% CI limit of the SIR (6.75) from the historical comparison translates to an upper limit for the attributable risk of 1 intussusception case per 65,287 RV5 dose-1 recipients. CONCLUSION Among US infants aged 4 to 34 weeks who received RV5, the risk of intussusception was not increased compared with infants who did not receive the rotavirus vaccine.