A global outbreak of a highly lethal strain of influenza threatens to engulf Britain if the Government does not change its policy on how to deal with such a pandemic.

An influential group of scientists has warned the government to stockpile a second antiviral drug to fight a global influenza epidemic because of the threat posed by a drug-resistant form of pandemic flu.

They believe that relying on a stockpile of the antiviral Tamiflu could prove catastrophic if a pandemic strain of the influenza virus develops resistance to the drug, as indicated by recent studies on the H5N1 strain of avian flu.

The H5N1 virus has spread to many populations of domestic and wild birds and has crossed into the human population several times, infected 258 people worldwide, and killed 153. Scientists fear that if H5N1 mutates to make it easier to spread from person to person, it could cause a global epidemic of highly lethal influenza, which would be made far worse if the virus is also drug-resistant.

The report by scientists drawn from the Royal Society and the Academy of Medical Sciences warned that Tamiflu stocks need to be bolstered with a supply of Relenza, the second antiviral, in case drug resistance develops.

Professor Sir John Skehel, a leading expert on influenza who chaired the scientific panel, said: "New evidence that H5N1 can develop resistance to Tamiflu indicates a combination of antivirals should be stockpiled by the UK. The Government has 14.5 million courses of Tamiflu to cover about a quarter of the population but the scientific panel pointed out that H5N1 has already developed resistance to the drug.

In one study, for instance, two out of eight patients in Vietnam who became infected with H5N1 developed drug resistance to Tamiflu. Both died.

"The Government was right to order Tamiflu in early 2005," Sir John said. "But we are concerned that it is not updating its plans as what we know about influenza changes."

Professor Neil Ferguson of Imperial College London, a member of the panel, said the "nightmare scenario" was that as Tamiflu was used to treat patients with pandemic flu, a drug-resistant strain emerged to become the dominant form of virus. "This is why we need to have a back-up plan," Professor Ferguson said.

Tamiflu, which is made by Roche, and Relenza, made by GlaxoSmithKline, are neuraminidase inhib-itors - they block a key viral protein - but they work in different ways.

Tamiflu comes in tablets while Relenza is taken with an inhaler. Sir John added: "If the virus that comes along was resistant to Tamiflu and not to Relenza, then we really have to have a stockpile of Relenza as well."

The panel of scientists also recommended that the Government should appoint a "influenza tsar" to take charge of giving high-level, independent advice to the Cabinet's ministerial committee on influenza. Sir John said: "You would look for the best possible person you could find. This specialist would sit alongside the Government's chief medical officer and chief scientific adviser to complement their roles and contribute relevant expertise."

"The UK is recognised as one of the most prepared countries in the world. However, research in this area must continue and up-to-date scientific information should be central to the Government's decision-making process," he said.

Fighting the virus


Also known as oseltamivir. Works by blocking neuraminidase, a protein that allows the flu virus to spread. Made by the Swiss company Roche and comes in tablets, pictured. Has been widely used in south-east Asia to treat the H5N1 strain of avian flu, which has killed about half of the people it is known to have infected.


Also known as zanamivir. Works by inhibiting neuraminidase, so preventing the spread of the virus within the body. It is made by GlaxoSmithKline and is administered through an inhaler rather than orally. Like Tamiflu, Relenza works best when given to a patient within 24 hours of the first symptoms appearing.