Pharmaceutical giant GlaxoSmithKline revealed today that a bird flu vaccine it is developing for humans has proved effective in clinical trials.
The UK-based firm said the vaccine to combat the deadly H5N1 strain of avian flu had been found to have an effect at very low doses.
Europe's largest drugs company said that over 80 per cent of subjects who received 3.8 micrograms of antigen, or active ingredient, during the clinical trials had demonstrated a "strong" immune response.
The size of the dose is significant as pharmaceutical companies strive to identify the smallest effective dose they can in order to produce the greatest amount of shots from a quantity of vaccine.
More than 130 people have been killed across the world by the H5N1 strain of avian flu after coming into contact with infected birds.
Experts fear that the rapid spread of the disease could prompt a global flu pandemic if the virus mutates so that it is more easily transferable between humans.
Glaxo said that it intended to make regulatory filings for the vaccine over the coming months, with governments able to order it for delivery and stockpiling in early 2007.
Commenting, Glaxo chief executive JP Garnier said: "These excellent clinical trial results represent a significant breakthrough in the development of our pandemic flu vaccine."
"This is the first time such a low dose of H5N1 antigen has been able to stimulate this level of strong immune response."
Mr Garnier added that there was still "a lot more work to be done" in relation to the development of the vaccine, but stressed that the results of the clinical trial had given the company the confidence to continue with its current approach and to assess the ability of the vaccine to provide protection against other variants of the H5N1 strain.