HealthDay News — The risk of intussusception in infants and children after rotavirus vaccine administration is slightly higher in post-licensure studies than previously reported, but not enough to change clinical practice, findings from two new studies published in New England Journal of Medicine indicate.
The pentavalent rotavirus vaccine, Rotateq (RV5, Merck), was associated with approximately 1.5 cases of intussusception per 100,000 infants during a 21-day risk period after being administered the first dose of the vaccine, according to one study.
In a separate study, the relative risk for intussusception with the monovalent vaccine, Rotarix (RV1, GlaxoSmithKline), compared with Rotateq was 9.4 (95% CI 1.4-103.8).
The studies “provide the most comprehensive description of the risk of intussusception after immunization with each of the rotavirus vaccines in the United States,” Roger Glass, MD, PhD, of the National Institutes of Health, and Umesh D. Parashar, MB, BS, MPH, of the CDC, wrote in an accompanying editorial.
But the new findings are not likely to warrant a change in practice.
“What, then, is the message for the physician or nurse who administers rotavirus vaccines, and what is the implication for vaccine policy in developed countries?,” Glass and Parashar wrote. “Certainly, the abundance of evidence in the United States and beyond indicates that intussusception can occur as a result of vaccination with either [rotavirus vaccine], but the risk is low, on the order of approximately 1 to 5 cases per 100,000 infants, with wide confidence limits.”
Intussusception is a rare medical condition in which the intestinal shaft slides back onto itself that can lead to serious infection and bowel perforation. In 1999, Wyeth Lederle discontinued the tetravalent RotaShield rotavirus vaccine after reports of approximately one to two cases of intussusception per 10,000 patients in it’s first year on the market.
In 2006, the FDA approved the pentavalent Rotateq, followed by the monovalent Rotarix in 2008. The vaccines have been associated with significant declines in rotavirus-associated gastroenteritis cases in the United States.
A 2012 Harvard study found no increased risk for intussusception with either of the two new rotavirus vaccines; whereas a 2013 CDC study found an excess risk of 0.79 cases per 100,000 with RV5.
Data from the most recent studies suggest the risk of intussusception is slightly higher with either vaccine.
In the first study, W. Katherine Yih, PhD, MPH, from Harvard Medical School and the Harvard Pilgrim Health Care Institute in Boston, and colleagues examined medical record data from 2004 to 2011, including 507,874 first doses and 1,277,556 total doses of RotaTeq, and 53,638 first doses, and 103,098 total doses of Rotarix.
There was a significant elevation in the number of excess cases of intussusception per 100,000 recipients of the first dose of RV5 in primary analysis (attributable risk, 1.5 for the 21-day risk window). For RV1, the results of the primary analysis were not significant, but the analysis was underpowered, the researchers cautioned.
In the second study, Eric S. Weintraub, MPH, from the CDC, and colleagues examined the risk of intussusception after RV1 vaccination among infants aged 4 to 34 weeks in the United States from 2008 through mid-2013.
Among 207,955 doses (115,908 first doses, and 92,047 second doses) of RV1 administered, six cases of intussusception occurred. The intussusception risk attributable to the monovalent rotavirus vaccine was estimated at 5.3 per 100,000 infants vaccinated.
Among 1,301,810 doses of RV5, eight cases of intussusception were reported, but as 7.11 were expected, the relative risk was a nonsignificant 1.1.
“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,” Weintraub and colleagues wrote.
Glass and Parashar called the overall intussuseption risk low, noting “the major impact that these vaccines have had on the reduction of hospitalizations, emergency department visits, and in some cases, deaths from diarrhea,” and that “policy makers have concluded that rotavirus vaccine remains a valuable addition to the national program for childhood immunizations.”