The super-vaccine that beats ALL types of flu - and is 90 per cent effective

The "holy grail" of flu treatments, the jab would fight off everything from a winter virus to a bird flu outbreak.

Two injections could give long-lasting immunity, unlike the current vaccine which has to be given every year.

The jab, which has been developed by scientists at Cambridge biotech firm Acambis, may also work better than the existing jab, which only protects around three-quarters of those vaccinated.

The universal flu jab, which has just been tested on people for the first time, is also quicker and easier to make, meaning vast quantities could be stockpiled against a global outbreak of bird flu.

Flu kills up to 12,000 Britons each year, many of them elderly. But a pandemic of the human form of bird flu - which many believe is inevitable - could claim 700,000 lives in the UK alone.

Trials on humans show that the jab is safe, causing no side-effects other than the occasional red arm and high temperature associated with all vaccines.

The trials also show that it works fast to prime the immune system to produce antibodies capable of attacking the virus in up to 90 per cent of those tested.

The trials, carried out on healthy young adults in the U.S., follow animal experiments in which the jab saved the life of ferrets given a dose of flu strong enough to kill them five times over. Seventy per cent of vaccinated animals survived - but all those not given the vaccine perished.

Scientists at Acambis are working on perfecting the formulation and dose, ahead of larger scale human trials.

It is thought that two doses a month apart could protect against the bug for many years.

The vaccine will also be quicker and easier to make than the current version which is grown in hen's eggs - a time-consuming process that yields one shot of vaccine per egg.

The new vaccine is grown in huge vats with only two pints of liquid providing 10,000 doses. Normally, the vaccine would have to go through another five years of human trials before going on the market.

However, if a bird flu pandemic occurs, it could be made available more quickly.

Dr Michael Watson, of Acambis, said: "Our approach is very simple, it just churns out the vaccine. It is a very elegant approach to production."

The flu jabs already in use focus on two proteins on the surface of the virus. However, these constantly mutate, making it impossible for manufacturers to keep up with the creation of each new strain, be it winter flu or bird flu.

The new vaccine, called ACAMFLU-A, is based around a different protein, called M2, which has barely changed during the last 100 years.

Crucially, it is found in all types of influenza A, including winter flu and the H5N1 bird flu virus.

So lucrative is the market at least two other companies - including British-based biotech firm PepTcell and Swiss vaccine developers Cytos - are also racing to create a universal jab.

However, the Acambis version is one of the few to have reached the stage of being tested on humans.

John Oxford, Britain's leading flu expert, said: "There is nothing wrong with having a holy grail, something to aim for. If this can be grasped, it would be a wonderful beginning to the new year."

Professor Oxford, of Queen Mary's School of Medicine in Lonsomedon, added: "Several groups are working on this and one group might have a slightly different formulation and hit the jackpot."

Professor Ian Jones, a University of Reading virologist, said the jab could end the "scramble" to produce a new winter jab each year.

Cautioning that it is still years from the market, he added: "The fact that the vaccine is safe and appears to raise protective antibodies is very encouraging although larger trials and tests on a wider range of viruses will be needed before the full potential for pandemic protection can be assured."

News of Acamabis's trials comes only weeks after the inventor of the current flu jab warned it does not guarantee protection. Dr Graeme Laver said the jab left one in four of those vaccinated still be at risk of catching flu.

Talking of the vaccine which he co-developed more than 40 years ago, the Australian said: "I have never been very impressed with its efficacy. It it better than nothing and I wouldn't want to advise people not to take it, but you can't rely on it."

He added that best way to protect public health was to make drugs which fight the virus once it has struck, such as Tamiflu and Relenza.