Reports in the United States of cases of infants suffering a serious bowel condition as a result of taking a new vaccine against the rotavirus, have prompted the U.S. Food and Drug Administration (FDA) to issue a warning about the drug.
The FDA is alerting health-care providers and consumers about the possible dangers associated with the vaccine RotaTeq.
RotaTeq has been linked to as many as 28 cases of a condition, called intussusception, where the intestine becomes blocked or twisted and one portion telescopes into a nearby portion, causing an intestinal obstruction which can be life-threatening.
The 28 cases included 16 infants who required intestinal surgery but there have been no reports of deaths.
The FDA says it is unclear how many of the cases were caused by the vaccine as the condition can occur in the absence of vaccination.
The FDA says about 3.5 million doses of Merck's RotaTeq have been distributed in the United States since its approval in February 2006, and although 28 reported cases does not exceed the number that might be expected, it has issued the warning to encourage reports of any additional cases.
The FDA Web site has issued the warning in order to remind people that intussusception was a potential complication of RotaTeq.
Although intussusception causes intense abdominal pain, most infants who are treated within 24 hours recover completely.
However a delay in treatment can result in serious complications, including tissue damage, perforation of the bowel and death.
Problems with the bowel initiated the recall in 1999 of Wyeth's RotaShield vaccine against rotavirus, which causes serious diarrhea and is a leading cause of hospitalization for infants.
Merck says RotaTeq was tested in trials involving 70,000 infants, and that little difference in cases of the bowel ailment were seen in those given the vaccine and those given placebos.
Within one year of treatment, it seems 13 cases of the bowel problem were detected among infants that received RotaTeq, compared with 15 cases among those receiving placebos.
Following approval by the FDA, a reporting system was created that allowed doctors and parents to report any problems among infants that received the vaccine and Merck says it would be difficult to determine how many, if any, of the 28 cases of intussusception reported under the surveillance system were due to the Merck vaccine and most could well be naturally occurring cases, given the product's safety in large clinical trials.
Rotavirus sickens about 2.7 million children younger than 5, sends up to 70,000 to the hospital and causes 20 to 70 deaths each year in the U.S.