In a Food and Drug Administration (FDA) news release yesterday, the agency is recommending that health care provider temporarily suspend the use of the Rotarix vaccine for rotavirus immunization due to the detection of pig virus DNA in the vaccine.

The DNA from the pig virus known as porcine circovirus 1 (PCV1) was discovered by an independent US academic research team, with follow up testing by the FDA and the manufacturer, GlaxoSmithKline (GSK) confirming the findings.

PCV1 is not known to cause disease in humans or other animals. GSK says that PCV1 is a common virus that is frequently eaten in meat products with no illnesses reported. Currently scientists are trying to determine whether the vaccine contains just fragments of the virus or whole virus that is capable of replicating.

It was also confirmed by scientists that this pig virus component has been in the vaccine since the earliest stages of development, the clinical trials.

FDA estimates show that 1 million US children have received the vaccine. This vaccine is given by mouth to young children for the prevention of rotavirus, a diarrheal disease that was responsible for 50,000 hospitalizations and several dozen deaths annually in the US prior to immunization.

Rotarix was licensed by the FDA in 2008.

The majority of rotavirus vaccines, up to 75%, prescribed by doctors are RotaTeq, a three dose oral vaccine manufactured by Merck. Preliminary testing of RotaTeq has not shown the presence of PCV1. RotaTeq was FDA licensed in 2006.

Rotarix is likely to continue to be used in many countries where the benefits of the vaccine surely outweigh the theoretical risk of harm.

In much of the developing world, rotavirus is estimated to be responsible for the deaths of 500,000 infants due to severe diarrhea and dehydration.