When a vaccine for rotavirus debuted in 1998, it was hailed as a huge plus for children's health. Before that, rotavirus killed more than 400,000 young children a year worldwide by causing severe diarrhea. Problem solved? Not quite.
Shortly after the Rotashield vaccine was introduced, doctors noticed an increase in cases of a serious intestinal problem called intussusception, when the intestine doubles back into itself. It is fatal if not treated, sometimes with emergency surgery.
Investigations determined that Rotashield, made by Wyeth (now part of Pfizer), increased a baby's risk of intussusception up to 30 times. As a result, the vaccine was yanked off the market in 1999.
The scientists never did figure out why the vaccine increased the risk of the intestinal problem. Newer rotavirus vaccines were developed, tested and licensed in 2006 and 2008. (Here's an NPR story on efforts to develop a safer vaccine.)
But concerns persist, fueled by two recent studies that found a fivefold increased risk of intussusception in babies in Australia and Mexico during the first week after they were given the vaccine.
So researchers looked at a big database of American children who had been given the new RotaTeq vaccine (made by Merck) between 2006 and 2010. They looked at 786,725 doses, of which 309,844 were first doses. They found no increase in intussusception. The results were published in JAMA, the Journal of the American Medical Association.
"The benefits of rotavirus vaccine do outweigh risks," says Irene Shui, an epidemiologist at Harvard Medical School and Harvard-Pilgrim Health Care Institute who is the lead author of the study. This study was funded in part by a contract with the Centers Disease Control and Prevention.
But she told Shots that that doesn't mean that these new vaccines are completely risk-free. "It's important for the public to realize that every treatment or intervention does have some risk." This study, she says, will help parents get a better grasp on those risks.
If you're interested in more details, there's a JAMA video with Shui.