BRITISH scientists have invented a radical bird flu vaccine.

Once a pandemic strain is identified it could be ready in days, say its makers.

Enough could be ready in three weeks to protect the entire population.

The vaccine is administered by a gaspowered canister which is placed on the skin. No needles are involved.

There are plans to turn supermarkets into mass vaccination centres with staff there giving the one-shot dose.

The breakthrough is a result of work by a team at University College London and Oxford company PowderMed, which has developed the vaccine. Dr Clive Dix, head of PowderMed, said: "This is a huge step forward for vaccines."

Experts say it could be key to preventing an estimated 50,000 deaths in Britain should a pandemic hit.

"This is really our last chance of a vaccine for everyone," said Professor Peter Dunnill of UCL, who has spent the last year developing the manufacturing process. Professor Dunnill added: "We believe we can convert existing drug factories to produce this new type of vaccine very quickly. It actually grows on bacteria and is very quick to produce."

However, he warned that because of the speed at which a pandemic would spread, governments would need to bypass several of the safety trials normally required for such a widely available drug.

He said: "There is definitely a safety issue here. But we believe that the benefits of a vaccine in large enough quantities to treat the entire global population far outweigh the risks."

A spokesman for the Department of Health said: "We have been in talks with PowderMed and they are keeping us abreast of the latest developments. The technology is very promising but is in the very early stages of development."

Traditional flu vaccines contain a harmless amount of the virus to trigger the body's immune system.

However, the new type contains a key protein taken from the DNA of the strain of flu being protected against.

This triggers the body's immune system in exactly the same way as conventional vaccines, but using a far smaller quantity of vaccine. Dr Dix added: "Seven days after the pandemic strain of flu is identified, we will be ready to start manufacturing. The delay is actually building the needleless device we use to deliver the vaccine, but we are now ready to begin manufacturing if we can get government backing."

The National Institute for Biological Standards and Control, which tests vaccines for the Government, would be in the front line of a UK response to a pandemic.

Director Stephen Inglis said DNA vaccines are interesting but are too new to deploy on the mass scale needed in a pandemic. He said: "There is a big gulf between something in the early stages of development and deployment on a pandemic situation. It would be a big step in the dark."

The Government said today that football matches and pop concerts will be banned if there is a bird flu pandemic.

Health Secretary Patricia Hewitt said that "mass gatherings" of people would have to be restricted to stop the disease spreading.

Emergency powers to restrict travel, visit the theatre and go to the cinema are also likely as ministers invoke the Civil Contingencies Act.

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