U.S researchers have made a major medical breakthrough in developing a flu vaccine which could offer life-long protection against the illness, according to a report in the latest edition of science journal Nature Medicine.
Trials on animals show the vaccine, which homes in on a stable part of the flu virus, is effective and now studies using human patients is necessary before it can be approved for distribution and sale.
Conventional flu vaccines target the mutating part of the virus but as these are continually changing, flu vaccines must be altered and administered each year, based on World Health Organization (WHO) analysis of circulating flu types.
The WHO annually makes recommendations for each hemisphere about the flu strains that are likely to be prevalent for the coming winter.
University of London flu expert Prof John Oxford, said the preliminary finding of the never-ending flu vaccine tests were particularly promising, calling it a "red letter day for science."
"This is a leap forward compared to anything done recently. They have good animal data, not just in mice but in ferrets and monkeys too. And they've done it with the bird flu virus H5N1," he said.
"It's a very good stepping stone. Ultimately, the hope is to get a vaccine that will cover a pandemic virus."
Professor of Vaccinology at University Prof Sarah Gilbert, said: "This is an exciting development, but the new vaccines now need to be tested in clinical trials to see how well they work in humans."
This will be the next stage of research, which will take several years. So we are still some way from having better flu vaccines for humans."
Experts said in the meantime, people should continue to get an annual flu shot as it is still the most effective way to protect oneself against infection.