Slight Increase in Intussusception Rate After Newer Rotavirus Vaccines

May 17, 2013

By Will Boggs, MD

NEW YORK (Reuters Health) May 17 - The risk of intussusception increases slightly in the days after receiving the RotaTeq (RV5) and Rotarix (RV1) rotavirus vaccines, according to a report from the U.S. Centers for Disease Control and Prevention (CDC) published May 13 in Pediatrics.

Still, "the vaccine is generally safe and the benefits of the vaccine far outweigh the small risk," Penina Haber from CDC's National Center for Emerging and Zoonotic Infectious Diseases, Atlanta, Georgia told Reuters Health in an email.

An earlier rotavirus vaccine, RotaShield, was withdrawn from the U.S. market because of its association with intussusception, but the two new live, oral rotavirus vaccines were not associated with an increased risk of intussusception in two large clinical trials. Their use has, however, been associated with an annual decline of around 40,000 gastroenteritis hospitalizations in 2008 and 2009 in U.S. children, which was associated with an estimated $140 million savings in treatment costs.

In the face of recent post-licensing reports from Australia and Mexico demonstrating a transient increase in the risk of intussusception in the first week after the first dose of RV1 or RV5, Haber and colleagues evaluated the possible temporal clustering of intussusception reports using data from the Vaccine Adverse Event Reporting System (VAERS) collected after more than 47 million RV5 doses. They also describe intussusception reports after RV1 vaccination.

VAERS received 584 confirmed intussusception reports after RV5 vaccination between 2006 and 2012, with the onset peaking three to six days after dose 1. Other reported adverse events peaked during days 0 to 1 after dose 1.

There was also a clustering of events on days 2 to 6 after dose 2, but none after dose 3.

Based on the overall number of doses of RV5 so far, these events translate into an excess risk (over the background rate) of intussusception of 0.74 events per 100,000 vaccinated infants after dose 1, 0.21 events per 100,000 after dose 2, and a 0.16 per 100,000 reduced risk after dose 3.

The overall excess risk of intussusception after all three doses of RV5 is 0.79 events per 100,000 vaccinated infants, or 33 additional events per year in the U.S.

The researchers were unable to quantify the risk after RV1 due to the lower vaccine uptake compared with RV5, but the similarity of clustering of cases during days 3 to 6 or 4 to 7 suggests a potential increased risk for both vaccines.

Haber advises physicians to be aware that there may be a small risk of intussusception after the first dose but to continue to recommend the vaccine as its documented benefits "far outweigh the small risk of intussusception."

"The risk can be minimized by adhering to the recommended vaccination schedule, especially administering the first dose before 15 weeks of age when the risk of intussusception is lower," Haber added.

"For physicians who recall the short history of RotaShield, an earlier rotavirus vaccine removed from the market in 1999 because of its own association with intussusception, these findings provide further evidence that the risks of today's vaccines are vastly smaller than those of that earlier product," Dr. Jason L. Schwartz from Princeton University's Center for Human Values in Princeton, New Jersey, told Reuters Health. "Also, the substantial benefits of current rotavirus vaccines in reducing hospitalizations of children have been demonstrated in their post-licensure use, another important distinction from the experience with RotaShield in the 1990s."

"Frank discussions about the limited, known risks of childhood vaccines -however uncommon they may be--may be understandably difficult for advocates of vaccination working to preserve public support for childhood vaccines in the face of vocal, passionate critiques of vaccine safety from some parents and celebrities," Dr. Schwartz said. "Yet careful research on these areas and dissemination of findings on both the benefits and risks of vaccination is essential for helping physicians, patients, and the general public all better understand why the public health community continues to believe so strongly in vaccination."

SOURCE: http://bit.ly/12Bm9nV

Pediatrics 2013.

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