Rotavirus can cause fatal diarrhea. Both vaccines target the virus, but pieces of DNA from porcine circovirus (PCV) have been found in both companies' products.
The FDA's decision follows a May 7 recommendation by its advisory panel, which ruled that the risk to humans from the pig virus was theoretical at best. It called for continued use of the vaccines, saying their benefits outweighed any potential risk.
Some strains of the pig virus are believed to cause a wasting syndrome in young piglets, marked by diarrhea and an inability to gain weight, but they are not known to injure humans. Tests found DNA from the virus in master cells used to make the Glaxo's product.