Vaccinating children against rotavirus may indirectly protect adults too, study finds

Pediatric rotavirus vaccination also indirectly protects unvaccinated adults from the highly contagious cause of severe diarrhea and vomiting, suggests a new study published in Clinical Infectious Diseases and available online. The findings suggest pediatric immunization against the virus may be more cost effective than previously thought, given rotavirus-related health care costs among adults.

Before the vaccine, rotavirus caused an estimated 24 million outpatient visits, 2.4 million hospitalizations, and 453,000 deaths in infants and young children worldwide each year. Following the introduction of the pediatric rotavirus vaccine in the United States, declines in the disease have been seen in both vaccinated and unvaccinated children.

Evan J. Anderson, MD, now at Emory University, and a team of researchers at Northwestern Memorial and Children's Memorial Hospitals in Chicago looked into whether the vaccine's benefits extended to unvaccinated adults. They compared the prevalence and genotypes of rotavirus in stool samples collected from approximately 3,500 adults before widespread implementation of pediatric rotavirus vaccination (2006-2007) with the prevalence in samples collected from 2008 to 2010. The researchers found the number of unvaccinated adults who had rotavirus was almost halved in the years after the vaccine was introduced for use in children in the U.S.

"In adults with diarrhea who see the doctor and who have testing for bacterial infections, we noticed an almost 50 percent decrease in rotavirus," said Dr. Anderson. With previous research estimating $152 million in total adult inpatient hospital charges related to rotavirus each year in the U.S., this latest data may make pediatric vaccination "much more cost effective than previously believed."

Dramatic declines in rotavirus prevalence were evident in both adults admitted to the hospital and in those treated as outpatients. The findings suggest that "vaccinating children can protect adults from rotavirus by decreasing the amount of rotavirus circulating in the community," Dr. Anderson said. Because rotavirus genotypes change from year to year, the researchers also noted that "ongoing surveillance is needed to determine whether this impact is sustained."

Rotavirus is the leading cause of severe acute gastroenteritis (vomiting and severe diarrhea) among children worldwide. Two different rotavirus vaccines are currently licensed for use in infants in the United States. The vaccines are RotaTeq® (RV5) and Rotarix® (RV1). Before being licensed, both vaccines were tested in clinical trials and shown to be safe and effective. In these studies, during approximately the first year of an infant’s life, rotavirus vaccine was found to prevent almost all (85%-98%) rotavirus illness episodes that were severe and to prevent 74%-87% of all rotavirus illness episodes.

The positive effect of pediatric rotavirus vaccination programs on the prevalence of disease among both young and old, vaccinated or not, underscores the need to support and encourage vaccination, Dr. Anderson said. "By improving the health of children, we indirectly improve the health of adults."