UPDATE 1-Rotavirus vaccines cut diarrhea sickness in U.S.

(Adds quotes from researchers)

By Maggie Fox, Health and Science Editor

WASHINGTON, Oct 25 (Reuters) - An oral vaccine for diarrhea reduced hospitalizations of children with rotavirus by more than 70 percent in some parts of the United States, saved money and protected unvaccinated children, researchers reported on Saturday.

One study by vaccine maker Merck and Co.(MRK.N) showed the vaccine eliminated emergency room visits for the strains of rotavirus targeted by the vaccine last year, while others showed clear benefits of the vaccine, which prevents the most common cause of severe diarrhea.

Irini Daskalaki of Drexel University College of Medicine reported that hospitals in North Philadelphia had seen a 70 percent drop in rotavirus-associated hospitalizations since rotavirus vaccinations began in 2006.

The number of babies aged 6 to 11 months admitted to the hospital with rotavirus plummeted by 94 percent, Daskalaki told a meeting of the American Society of Microbiology and the Infectious Diseases Society of America.

"The extent of the decrease in cases ... is unprecedented," Daskalaki wrote in a summary released before the presentation.

Merck's Rotateq was recommended in 2006 for routine immunization of U.S. infants, while GlaxoSmithKline Plc's (GSK.L) Rotarix, was approved by the U.S. Food and Drug Administration in April. Both are considered equally safe.

Rotavirus is the leading cause of severe gastroenteritis, with vomiting and diarrhea, in infants and young children.

Before routine vaccination, the condition sent 410,000 children to a doctor every year in the United States, with more than 200,000 needing emergency care and 20 to 60 dying.

Globally, rotavirus kills 1,600 children under age 5 every day -- 500,000 a year.

Doctors had been desperate for a vaccine to prevent the highly contagious infection. But the first one, sold by Wyeth WYE.N, was pulled from the market in 1999 after it was linked to a rare, life-threatening type of bowel obstruction known as intussusception.

The new vaccines do not have that problem. The World Health Organization is working to make both vaccines more available in developing countries.

Merck researchers looked at a database of physician records on 61,000 infants.

"Rotateq provided 100 percent protection against hospital and emergency department visits when administered during routine public health practice," Merck's Christopher Mast told a news conference.

Children still became ill with diarrhea -- they simply were not being made sick by the most dangerous strains of rotavirus targeted by the vaccine, Merck said.