Large pre-licensure clinical trials of both RotaTeq and Rotarix did not find an increased risk for intussusception among vaccine recipients. A large post-licensure study of more than 1.2 million rotavirus vaccine recipients found a very small increased risk of intussusception (1 to 1.5 additional cases of intussusception per 100,000 vaccinated infants) in the 7 to 21 days following the first dose. No increased risk of intussusception was found after the second or third doses. CDC and the Food and Drug Administration (FDA) continue to believe that the benefits of rotavirus vaccination outweigh the risks associated with vaccination and that routine vaccination of infants should continue.
A study conducted by the CDC Vaccine Safety Datalink (VSD) between May 2006 to February 2010 found no increased risk of intussusception following vaccination with RotaTeq. However, the study indicated an increased risk of intussusception following dose 1 and dose 2 of Rotarix. CDC estimates that there is a small increased risk of intussusception, usually within the first week after dose 1 or dose 2 of rotavirus vaccine, resulting in one additional case for every 20,000 to 100,000 U.S. infants who receive the vaccine.