Risk of Intussusception after Monovalent Rotavirus Vaccination

BackgroundAlthough current rotavirus vaccines were not associated with an increased risk of intussusception in large trials before licensure, recent postlicensure data from international settings suggest the possibility of a small increase in risk of intussusception after monovalent rotavirus vaccination. We examined this risk in a population in the United States. MethodsParticipants were infants between the ages of 4 and 34 weeks who were enrolled in six integrated health care organizations in the Vaccine Safety Datalink (VSD) project. We reviewed medical records and visits for intussusception within 7 days after monovalent rotavirus vaccination from April 2008 through March 2013. Using sequential analyses, we then compared the risk of intussusception among children receiving monovalent rotavirus vaccine with historical background rates. We further compared the risk after monovalent rotavirus vaccination with the risk in a concurrent cohort of infants who received the pentavalent rotavirus vaccine. ResultsDuring the study period, 207,955 doses of monovalent rotavirus vaccine (including 115,908 first doses and 92,047 second doses) were administered in the VSD population. We identified 6 cases of intussusception within 7 days after the administration of either dose of vaccine. For the two doses combined, the expected number of intussusception cases was 0.72, resulting in a significant relative risk of 8.4. For the pentavalent rotavirus vaccine, 1,301,810 doses were administered during the study period, with 8 observed intussusception cases (7.11 expected), for a nonsignificant relative risk of 1.1. The relative risk of chart-confirmed intussusception within 7 days after monovalent rotavirus vaccination, as compared with the risk after pentavalent rotavirus vaccination, was 9.4 (95% confidence interval, 1.4 to 103.8). The attributable risk of intussusception after the administration of two doses of monovalent rotavirus vaccine was estimated to be 5.3 per 100,000 infants vaccinated. ConclusionsIn this prospective postlicensure study of more than 200,000 doses of monovalent rotavirus vaccine, we observed a significant increase in the rate of intussusception after vaccination, a risk that must be weighed against the benefits of preventing rotavirus-associated illness. (Funded by the Centers for Disease Control and Prevention.) Vaccination has been associated with a decline in rotavirus-associated illness, but concern about intussusception remains. In this CDC report, the monovalent rotavirus vaccine was associated with a slight increase in intussusception risk, as compared with the pentavalent vaccine. The first licensed rotavirus vaccine (RotaShield) was withdrawn from the U.S. market in 1999 because of an increased risk of intussusception.(1) Subsequently, two rotavirus vaccines have been licensed in the United States: RotaTeq (a pentavalent rotavirus vaccine) in 2006 and Rotarix (a monovalent rotavirus vaccine) in 2008.(2),(3) The two vaccines underwent prelicensure clinical trials involving 60,000 to 70,000 infants each, in which no increased risk of intussusception was identified.(4),(5) Postlicensure monitoring in the Vaccine Safety Datalink (VSD) project has not found an increase in the risk of intussusception after pentavalent rotavirus vaccination.(6),(7) At the time of the ...