New Rotavirus Vaccines Working without Serious Side Affects
There is good news concerning the re-introduction of two rotavirus vaccines into the nation’s population in 2006 and 2008, based on research conducted by the University of Michigan.
Researchers there say they can find no evidence that the vaccines are affecting people infected with the rotavirus in the same way that led to the original vaccine being pulled from the marketplace in 1999. At the time, the vaccine was blamed for serious bowel obstructions that in some cases proved fatal. Rotavirus causes vomiting, abdominal pain, severe diarrhea and frequently requires hospitalization for young infants and children. Rotavirus was once the leading cause of gastrointestinal illness among children in the U.S. The vaccine, while beneficial in treating the virus, also caused, in some cases, a bowel obstruction called intussusception. Once the connection was made, the vaccine was removed from pharmacies and work began in laboratories to improve the drug.
University of Michigan pediatrician Joseph S. Zickafoose, has led the study on the safety of the new rotavirus vaccines described in a recent issue of Archives of Pediatric Adolescent Medicine. He says the two updated versions of the vaccine are preventing infection by rotavirus while not causing an increase in incidents of the bowel obstruction.
“We always need to carefully weigh the risks and benefits of childhood vaccines. Fortunately, our results suggest that rotavirus vaccines have not increased the rate of intussusception in the U.S.,” says Dr. Zickafoose. And while several international studies have shown that, among vaccinated infants, the two latest rotavirus vaccines may be associated with a small increase in cases of intussusception they do not appear to increase the rate of hospitalizations for intussusception, at least in the United States.
More than 70 percent of infants in the U.S. have been vaccinated against rotavirus. The re-introduction of the vaccines is credited with reducing the number of diarrhea-related outpatient visits, emergency department visits, and hospitalizations among children.
Data used in the study came from the Healthcare Cost and Utilization Project’s Kids’ Inpatient Database, which is a sample of 80 percent of national pediatric discharges. The study focused on children younger than 1-year-old based on previous data which showed the most cases on intussusception occur within weeks of the vaccine being administered at ages 2-months, 4-months and 6-months old. The investigators examined data trends from the decade prior to vaccine re-introduction, 1997-2006, and then made comparisons to data after vaccine re-introduction. When comparing data, investigators expected to see 36 intussusception-related hospitalizations per 100,000 children under 1-year-old by 2009.
Despite the re-introduction of the vaccines, there were only 33.3 hospitalizations per 100,000 children in 2009, making it very unlikely that the vaccines led to additional cases.
The latest versions of the rotavirus vaccine were licensed following studies in over 70,000 children, which showed no increased risk for intussusception among those vaccinated. However, there has been lingering concern that a small amount of risk may have been missed in these studies.
“We hope that our study provides information that will continue to reassure parents that the benefits of rotavirus vaccine outweigh the risks,” says Zickafoose, lead author of the study.
Additional authors: Brian D. Benneyworth, M.D., M.S., Meredith P. Riebschleger, M.D., Claudia Espinosa M.D., Mattew Davis, M.D., M.A.P.P
Citation: Zickafoose JS, Benneyworth BD, Riebschleger MP, Espinosa CM, Davis MM. Intussusception hospitalizations before and after the reintroduction of rotavirus vaccine in the United States. Arch Pediatr Adolesc Med. Epub Jan. 2, 2012.
Reference: University of Michigan