UPDATE 1-Glaxo rotavirus vaccine appears safe--US FDA panel

(Adds panel member comments, details from meeting, byline)

By Kim Dixon

GAITHERSBURG, Md., Feb 20 (Reuters) - GlaxoSmithKline Plc's (GSK.L) infant vaccine to prevent diarrhea caused by the rotavirus appears safe and effective, based on available data, U.S. advisers said on Wednesday.

The Food and Drug Administration advisory panel voted that the 11 studies submitted by GlaxoSmithKline support the use of the oral vaccine, which aims to prevent severe infant diarrhea often caused by infection with the virus.

The FDA typically takes the advice of its expert panels.

The vaccine, called Rotarix and already approved in many countries, could compete with Merck & Co Inc's (MRK.N) RotaTeq vaccine in the United States, if approved by the FDA.

Approval in the United States could intensify the rivalry between the two drugmakers.

In a briefing prepared for the meeting, FDA staff had noted a statistically significant increase in deaths related to pneumonia compared with placebo in Glaxo's largest trial.

The panel was unanimous the vaccine appeared effective and voted 11-1 that it appeared safe. Most members were convinced by Glaxo's argument the pneumonia deaths were an isolated finding from a single study likely not due to the vaccine itself.

"I am not highly concerned about the pneumonia issue," said Melinda Wharton, a vaccine expert at the U.S. Centers for Disease Control and Prevention and panel member.

Vicky Debold, patient safety director at the National Vaccine Information Center, was the sole panel member to vote that the data does not support the vaccine's safety.

She noted the infants studied were all healthy and asked: "What happens when this vaccine is given to children in the real world?"

Rotavirus results in the hospitalization of about 55,000 children each year in the United States and the death of over 600,000 worldwide, according to the U.S. Centers for Disease Control and Prevention.

Glaxo said it plans several observational studies to monitor worrisome safety signals, including the pneumonia deaths, if the drug is approved in the United States.

"We have a high level of confidence in the safety of the vaccine," Glaxo's vice president for regulatory affairs Clare Kahn told the panel. (Reporting by Kim Dixon, editing by Richard Chang/Andre Grenon)