Officials from the US Food and Drug Administration (FDA) have advised physicians to temporarily suspend the use of Rotarix, a vaccine used to prevent rotavirus infection.
The FDA is concerned that the vaccine manufactured by GlaxoSmithKline is contaminated with a second virus, called PCV-1, which infects pigs and other species but is not known to cause illness in humans or any other animals.
The virus is believed to have come from the cell cultures used to make Rotarix, and there is no evidence that this finding poses a safety risk.
Because available evidence supports the safety of Rotarix, no medical follow-up is needed for patients who have been vaccinated with Rotarix.
Rotavirus can cause vomiting and diarrhoea in infants and children, causing around 500,000 deaths a year.
There are two licensed vaccines for rotavirus in the US: RotaTeq and Rotarix.
The FDA has recommended the precaution while the agency learns more about the situation.