THURSDAY, Jan. 24 (HealthDay News) -- A new study finds that vaccinating children against rotavirus may also help protect unvaccinated adults against the highly contagious virus that causes severe diarrhea and vomiting.

Before vaccination was introduced, rotavirus caused 2.4 million hospitalizations and more than 450,000 deaths in infants and children globally each year. After vaccination was introduced in the United States, declines in rotavirus infection were seen in both vaccinated and unvaccinated children.

This study examined whether the vaccine's benefits also extend to unvaccinated adults. The researchers compared the prevalence of rotavirus in stool samples collected from 3,500 adults in 2006 and 2007 -- before widespread implementation of rotavirus vaccination in children -- and in samples collected from 2008 to 2010.

There were nearly 50 percent fewer unvaccinated adults with rotavirus in the second round of samples, according to the study, which was published online Jan. 24 in the journal Clinical Infectious Diseases.

Significant declines were seen in both adults admitted to the hospital and those treated as outpatients.

Previous research estimated that adult inpatient hospital charges related to rotavirus are $152 million a year in the United States. These new findings suggest that vaccinating children against rotavirus may be "much more cost effective than previously believed," study author Dr. Evan Anderson, of Emory University in Atlanta, said in a journal news release.

"Vaccinating children may protect adults from rotavirus by decreasing the amount of rotavirus circulating in the community," Anderson said.

The findings highlight the need to support and encourage vaccination, he added. "By improving the health of children, we indirectly improve the health of adults," he said.

More information

The U.S. Centers for Disease Control and Prevention has more about rotavirus.