A serious global outbreak of the virus among human beings is becoming more likely, according to a report from the organisation which is expected to be published next month.

The warning came as British scientists published new data suggesting that avian flu may be much more common in human beings than previously realised, but is being misdiagnosed as diarrhoea and encephalitis (inflammation of the brain).

The US, French and Italian governments have all placed orders for avian flu vaccine, but the British Government has not. It believes — as the WHO has until now — that vaccines should be produced only when a pandemic emerges because they need to be based on the precise strain of the virus responsible.

The British plan for dealing with a new flu pandemic was produced in March 1997, and is now being updated. It acknowledges that if there is a pandemic, vaccine is likely to be sacrce and will have to be given to “priority groups” — healthcare workers, fire, police, armed services, utilities and undertakers.

Those with chronic respiratory or heart disease, women in the last third of pregnancy, nursing home residents and the elderly will be next in line. “The public will need to be educated about the reasons for the vaccine not being generally avail-able,” the plan admits.

The plan is expected to include bans on football matches and pop concerts, to try to slow the spread of the disease. It is also likely to recommend stockpiling antiviral drugs, to blunt the impact of the disease before a vaccine is widely available.

“The plan is currently being brought up to date, and we are working closely with international organisations, researchers and industry to develop our plans” a health department spokeswoman said.

“This includes looking at issues such as the role of antivirals and vaccines as well as other public health measures which could help to slow the spread of a pandemic. A draft plan will published in the spring.”.

Klaus Stohr, head of the influenza team at WHO, now fears that once a pandemic starts there will not be time to produce sufficient vaccine. “When we realised H5N1 (the avian flu virus) was not going to be eradicated in poultry in Asia for at least another couple of years, that made the risk much higher,” Dr Stohr told New Scientist.

“Normally there is no point in stockpiling vaccine because you don’t know which flu will cause the next pandemic. It could be H7 or H9.”

The persistence of the H5N1 virus among birds in Asia, and growing evidence that it can transfer to human beings, are causing a change of mind. The latest thinking is that a generic H5 vaccine, even if it did not exactly match the virus, could provide worthwhile protection.

While it might not prevent people falling ill, it might stop them dying, experiments in animals suggest.

It would also be a useful first step towards providing immunity. People normally require two vaccinations to make them immune to a strain of flu they have not encountered before.

An H5 vaccine would “prime” the immune system so that a single shot of a specific pandemic vaccine would be all that was needed for immunity.

The US has already contracted for four million doses, while Italy and France said last week they were ordering two million doses each. “This is an option only for affluent countries, and then for a fraction of their population,” Dr Stohr said. “It won’t change a lot at the global level.”

The Department of Health said yesterday that because of the constant mutation of flu viruses it was impractical to stock large quantities of existing bird flu vaccine as it may not protect against a future strain of bird flu.

But it said that it was working closely with industry and experts to create vaccine seed materials that could be used to develop a vaccine.

“This work could be important in making sure that a safe and effective vaccine is available more quickly should HN51 emerge as a pandemic strain,” a spokeswoman said.

Clinical trials of a vaccine against the strain of avian flu now circulating in Asia are due to start soon in the US, and are also planned in Canada, Australia and Japan.

But even if the vaccine works, producing it could be a problem. There is only a two to three month “window” between runs of regular flu vaccine, and one leading manufacturer, Chiron, cannot start until problems of contamination at its Liverpool facility are solved.

Explore UK News

• Crime News

• Education News

• Health News

• Science News

• Scotland News

Times Recommends

• Olympic-size television coming to your town
• Mosley opens new front in battle for privacy
• Decorator fined for smoking in van