The rotavirus vaccine Rotarix may slightly increase the risk of intussusception, based on preliminary data from a postmarketing study in Mexico that prompted the Food and Drug Administration to approve label revisions.
The revisions to the warnings and precautions section and the postmarketing subsection of the adverse reactions section of the label were added to inform physicians of the new findings. An interim analysis of the data suggests an increased risk (1.8) of intussusception within the first 31 days after the first dose.
"For the United States, these findings translate to potentially 0–4 additional cases of intussusception hospitalizations per 100,000 infants within the first 31 days of receiving the first dose of Rotarix," the agency wrote in a Questions and Answers update released Sept. 22, 2010. The study did not look at RotaTeq.
Physicians should be aware of the data but "explain to parents and caregivers of infants that the benefits of vaccination with both Rotarix and RotaTeq outweigh any potential risks," the FDA said.
Parents should be informed of the signs and symptoms of intussusception, which include stomach pain, vomiting, diarrhea, blood in the stool, or change in bowel movements – especially within the first 7 days after the dose of the vaccine. Further analysis of the data revealed that most of the intussusception cases occurred within this time period.
The FDA and the Centers for Disease Control and Prevention encourage physicians to report intussusception or any adverse event after vaccination to the Vaccine Adverse Event Reporting System.