The babies developed intussusception, a serious and potentially life-threatening condition in which the intestine gets blocked or twisted.
Sixteen of the 28 babies required hospitalization and surgery. The other 12 needed enemas to reduce the intussusception. None died.
RotaTeq targets rotavirus, a leading cause of kids' diarrhea. The vaccine, approved by the FDA last year, is on the CDC's 2007 recommended child immunization schedule. It's given in three doses when babies are 2 to 6 months old.
It's not known whether RotaTeq caused the babies' intussusception. The number of reported cases is in line with expectations, says the FDA.
However, a different rotavirus vaccine, called RotaShield, was withdrawn from the market in 1999 after a rise in intussusception was noted after its use.
RotaTeq's label has been updated to reflect the intusssusception reports. But the vaccine's "dosage and administration schedule remains unchanged," says the FDA.
The FDA's Recommendations
The FDA's public health notification about the intussusception cases includes these recommendations:
"Parents should contact their child’s doctor immediately if the child has stomach pain, vomiting, diarrhea, blood in their stool or change in their bowel movements, as these may be signs of intussusception. It is important to contact the child’s doctor if there are any questions or if the child has any of these symptoms at any time after vaccination, even if it has been several weeks since the last vaccine dose."
The FDA also asks that any cases of intussusception be reported to the Vaccine Adverse Event Reporting System (VAERS), which is run by the FDA and CDC.
For a copy of the vaccine reporting form, call 800-822-7967 or go online to www.vaers.hhs.gov.
The 28 cases of intussusception were reported between the FDA's approval of RotaTeq on Feb. 3, 2006 and Jan. 31, 2007.
RotaTeq's intussusception risk was studied in approximately 70,000 infants -- half of whom got the RotaTeq vaccine; the other half got a placebo -- before the FDA approved RotaTeq.
Those studies showed "no significant increased risk of intussusception," notes an FDA public health notice.
The FDA also says that "the number of intussusception cases reported to date after RotaTeq administration does not exceed the number expected," based on unpublished CDC data.
According to the FDA, about 3.5 million doses of RotaTeq had been distributed in the U.S. through Feb. 1, 2007, but not all of those doses have been administered.
The 28 intussusception cases were reported after the first, second, and third doses of the vaccine. The cases occurred within 73 days after getting any of those doses; roughly half of the cases happened within 21 days.
The FDA's Past Comments
When the FDA approved RotaTeq just over a year ago, the FDA's Jesse Goodman, MD, MPH, called data from the vaccine's preapproval studies "reassuring."
But Goodman, who directs the FDA's Center for Biologics Evaluation and Research, also said at the time that "people would need to consider that [the studies] are not conclusive that this side effect could not potentially occur" and that the FDA had put in place "an extremely aggressive program to try to get as much information about the vaccine in its early period of use as possible."
Further studies are being done to probe the risk of intussusception and other serious events with RotaTeq.
RotaTeq's maker, the drug company Merck, is conducting a postmarketing study of approximately 44,000 infants. The CDC is doing its own study of about 90,000 infants, says the FDA. Merck is a WebMD sponsor.
WebMD contacted Merck for the company's comments.
In a news release emailed to WebMD, Merck states that intussusception is "a naturally occurring event in infants" that is estimated to occur in approximately one in 2,000 infants during the first year of life.
"Cases of intussusception can occur when no vaccine has been given, and the cause is usually unknown," Merck states.
The news release also includes comments from Mark Feinberg, MD, PhD, vice president of policy, public health, and medical affairs for Merck Vaccines.
"It is common for post-marketing experience information with a vaccine to be reported to VAERS and for the prescribing information to be updated accordingly," Feinberg says, in the news release.
Feinberg says public health and patient safety are Merck's "highest priorities" and that Merck is "very confident" in the data supporting RotaTeq's safety profile from its preapproval study.
RotaShield, the vaccine that was withdrawn from the market in 1999, was made by the drug company Wyeth.
Wyeth is a WebMD sponsor.