Rotavirus vaccine makers say they believe a contaminant of the pig enzyme trypsin, used in the vaccine's manufacture, is responsible for the pig virus detected in both GlaxoSmithKline's (NYSE: GSK) Rotarix and Merck's (NYSE: MRK) RotaTeq. The virus is believed to be nonthreatening to humans, and an FDA panel on Friday gave physicians the go-ahead to continue their use.
Researchers studying Rotarix stumbled on DNA from porcine circovirus type 1 (PCV1) while using new molecular detection techniques. They found the matter in the cell bank and seed from which the vaccine is derived, meaning the contamination goes back to the vaccine's early stages of development. The FDA had recommended a "temporary suspension" in the use of Rotarix until the regulator could find out more.
Since then, more sensitive tests have yielded traces of type 2 of the virus in Rotarix, as well as PCV1 in Merck's RotaTeq, which had been thought to be PCV-free.
- here's an LA Times summary