NEW YORK (Reuters) - The Food and Drug Administration said on Tuesday it was notifying health-care providers and consumers about reports of some 28 cases of infants suffering a serious bowel condition after receiving Merck & Co’s new vaccine against the rotavirus.
The FDA said it was not immediately clear how many of the cases were caused by the vaccine. It said the condition, known as intussusception, can occur in the absence of vaccination.
About 3.5 million doses of Merck’s RotaTeq have been distributed in the United States since its approval in February 2006, the FDA said.
The agency said the 28 reported cases do not exceed the number that might be expected, but it issued the warning to encourage reports of any additional cases.
The agency also said it was issuing the notification, which also was posted on the FDA Web site, to remind people that intussusception was a potential complication of RotaTeq.
The potentially life-threatening condition occurs when the intestine gets blocked or twisted and one portion telescopes into a nearby portion, causing an intestinal obstruction.
Merck said on Tuesday it had updated the prescribing information on the vaccine’s label insert to include post-marketing reports of intussusception and hematochezia, or bleeding from the intestines, to the Vaccine Adverse Events Reporting System, a national vaccine safety surveillance program.
Intussusception causes intense abdominal pain. Most infants who are treated within 24 hours recover completely but a delay in treatment can result in serious complications, including tissue damage, perforation of the bowel and death.
The bowel problem spurred the recall in 1999 of Wyeth’s RotaShield vaccine against rotavirus.
The virus causes serious diarrhea and is a leading cause of hospitalization for infants.
Dr. Michelle Goveia, a Merck medical director, said 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, 13 cases of the bowel problem were detected among infants that received RotaTeq, compared with 15 cases among those receiving placebos, Goveia said.
“We believe we designed the study rigorously and we didn’t see a ... relationship,” she said.
After RotaTeq was approved, a reporting system was created that allowed doctors and parents to report any problems among infants that received the vaccine.
Goveia said 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.
But she speculated most were naturally occurring cases, given the product’s safety in the large clinical trials.