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By Lisa Richwine
WASHINGTON, Sept 22 (Reuters) - GlaxoSmithKline Plc's (GSK.L) vaccine against a diarrhea-causing virus may be linked to a small increase in a rare but life-threatening type of bowel obstruction, U.S. health officials said on Wednesday.
Early data from a study in Mexico suggested infants given the Rotarix vaccine may face a higher chance of an intestinal problem known as intussusception for 31 days after their first dose, the Food and Drug Administration said on its website.
The vaccine prevents infection with rotavirus, the world's leading cause of severe diarrhea and dehydration in infants.
A rotavirus vaccine from Wyeth, now part of Pfizer Inc (PFE.N), was pulled off the market in 1999 after it was linked with intussusception.
The FDA said it was reviewing the findings for the Glaxo vaccine.
"Although the results are preliminary and will require further evaluation, FDA approved revised labeling to inform healthcare providers of this finding," the agency said.
Glaxo's rotavirus vaccine sales in 2009 were $440 million globally, including $118 million in the United States. It is a relatively small product for the British drug giant with total 2009 sales of $44 billion.
The benefits of rotavirus vaccines continue to outweigh risks, the FDA said.
Any increased bowel risk with Rotarix would be small, the agency said. For the United States, the findings translated to up to four additional cases of intussusception hospitalizations per 100,000 infants within the first 31 days. Most cases in the Mexican study occurred in the first seven days.
Glaxo said a final analysis of the Mexican study would be done at the end of 2011.
"GSK remains confident in the safety profile of Rotarix and is committed to the highest standards of patient safety," the company said in a statement.
Doctors should follow up on symptoms such as severe abdominal pain, persistent vomiting, and bloody stools as a precaution, the company said.
Merck & Co (MRK.N) sells a rival vaccine called RotaTeq. Current information does not suggest an increased bowel risk with RotaTeq but studies are ongoing, the FDA said.
Rotavirus kills more than 500,000 infants each year, mostly in low- and middle-income countries. In the United States, deaths from the virus are rare, but it caused more than 50,000 U.S. hospitalizations annually before Merck's vaccine won FDA approval in 2006.
Glaxo shares slipped 1.2 percent to $39.88 in afternoon trading on the New York Stock Exchange. (Reporting by Lisa Richwine; Editing by Maureen Bavdek and Robert MacMillan)