Regulators in the USA have advised doctors to temporarily suspend use of GlaxoSmithKline’s rotavirus vaccine Rotarix after impurities in the product were discovered.

The US Food and Drug Administration has been informed by the company that components of an extraneous virus, PCV1, are present in Rotarix. The agency says that “there is no evidence at this time that this finding poses a safety risk” but is still recommending suspension.

The agency said that it will continue to gather more information about the PCV1 components in Rotarix, including whether intact virus, as opposed to DNA fragments, is present. In four to six weeks, it will convene an expert advisory committee and make additional recommendations on the use of rotavirus vaccines.

Thomas Frieden, director of the Centers for Disease Control and Prevention, did say that rotavirus “causes so much severe illness and death that the known benefits of continued use of Rotarix far outweigh any theoretical risk of harm from the vaccine”. As a result, “we anticipate that many countries will decide to continue vaccinating with Rotarix while more information becomes known”.

That is the case in Europe where regulators said last week that no action was necessary at this point. However, the European Medicine's Agency's Committee for Medicinal Products for Human Use has now requested that GSK provide further information “as a matter of urgency” and called a meeting on March 23-24, with the participation of experts from the World Health Organisation, and international regulators including from Canada and the USA.

GSK notes that PCV-1, which is found in everyday meat products and is frequently eaten with no resulting disease, “does not multiply in humans and is not known to cause illness in humans”. The material was first detected following work done by a research team in the USA using a novel technique for looking for viruses, the firm says, adding that material from PCV-1 “has been present since the initial stages of the vaccine’s development in the cell bank and rotavirus seeds used as base production material”.

GSK added that it is now reviewing “how best to replace, in a timely way, the cell bank and virus seeds” and in the meantime will continue to manufacture Rotarix “to the existing approved production and quality standards to meet public health needs worldwide”. The company added that post-marketing surveillance data representing more than 69 million doses of Rotarix distributed reflect its “excellent safety profile”.

Rotarix is a big-seller for GSK and sales last year reached $440 million, and $118 million of that came from the USA, where most children receive Merck & Co’s rival product RotaTeq. In an investor note, analysts at JP Morgan said the US suspension was “insignificant” for the healthcare giant.