Vaccine helps prevent diarrhea in infants

WASHINGTON — A vaccine against rotavirus, the leading cause of diarrhea in infants, has led to a substantial drop in hospitalization and emergency-room visits since it came on the market two years ago, doctors reported Saturday.

A bonus: the vaccine seems to be preventing illness in unvaccinated children by cutting the number of infections that children can pick up and spread.

"We're a little surprised by the degree of impact, given the coverage we've achieved," said Jane Seward, of the federal Centers for Disease Control and Prevention (CDC).

Only about half of young children had received the vaccine, and very few had received all three doses when the studies were done.

Results were reported Saturday at an infectious-diseases conference in Washington, D.C.

Before the vaccine, more than 200,000 U.S. children were taken to emergency rooms and more than 55,000 were hospitalized each year with rotavirus, which causes vomiting and diarrhea, mostly from January through May. Worldwide, the virus kills 1,600 young children each day.

Since Merck's Rotateq came out in 2006, hospital visits and stays due to the virus have dropped 80 to 100 percent, studies by the CDC and several other groups show.

Last winter, rotavirus cases started and peaked two to three months later and were much less extensive than in previous years, CDC scientists said.

Hospitals in a network that tracks these cases for the CDC saw more than an 80 percent drop in admissions from them, one study showed.

Another study, by Merck, found a 100 percent drop in hospitalizations and ER visits during the 2007 and 2008 rotavirus seasons compared with previous ones.

The study was based on a review of health-insurance claims for about 61,000 infants and diagnoses by doctors in routine clinical practice.

Rotateq is an oral vaccine given at two, four and six months.

In June, a second rotavirus vaccine came on the market: GlaxoSmithKline's Rotarix. It requires only two doses, completed by four months.