Although 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.
Dr Eric Weintraub and colleagues examined this risk in a population in the United States.
Participants were infants between the ages of 4 and 34 weeks who were enrolled in 6 integrated health care organizations in the Vaccine Safety Datalink (VSD) project.
The research team reviewed medical records and visits for intussusception within 7 days after monovalent rotavirus vaccination from 2008 through 2013.
Using sequential analyses, the team then compared the risk of intussusception among children receiving monovalent rotavirus vaccine with historical background rates.
The researchers further compared the risk after monovalent rotavirus vaccination with the risk in a concurrent cohort of infants who received the pentavalent rotavirus vaccine.
During the study period, 207,955 doses of monovalent rotavirus vaccine were administered in the VSD population.
|Risk of intussusception after two doses of monovalent rotavirus vaccine was about 5.3 per 100,000|
|New England Journal of Medicine|
The team 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.
For the pentavalent rotavirus vaccine, 1,301,810 doses were administered during the study period, with 8 observed intussusception cases, for a nonsignificant relative risk of 1.1.
The team noted that 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.
The team found that 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.
Dr Weintraub's team concludes, "In 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."