The agency reported 28 cases of twisted intestines, a potentially life-threatening condition, after children were vaccinated with RotaTeq, which Merck sells to ward off childhood diarrhea.

The FDA isn’t clear, though, how many cases were actually due to the vaccine or occurred spontaneously. Of the 28 cases, 16 infants with intussusception required hospitalization and surgery on their intestine. No deaths due to intussusception were reported. This is the same problem that caused Wyeth to withdraw its RotaShield vaccine for childhood diarrhea in 1999.

At the time RotaTeq was approved, the FDA and Merck said clinical trials indicated the vaccine didn’t increase the risk of intussusception. But the drugmaker and the Centers for Disease Control and Prevention are conducting follow-up studies of more than 100,000 infants to monitor any long-term side effects. The FDA also is studying adverse event reports.

This is bad new for Merck, of course. Last year, RotaTeq, which is sold in 34 countries worldwide, generated $163 million in sales. Moreover, the company has repeatedly touted its prowess in vaccine development as crucial to engineering a turnaround.

Instead of being the proverbial shot in the arm, RotaTeq may prove to be a shot in the head.

[tags]Merck, RotaTeq, Vaccines[/tags]