GlaxoSmithKline, Europe's largest pharmaceutical group, claimed today that it could have a human vaccine to combat the deadly H5N1 bird flu virus by next year.

It said trials on 400 healthy adults aged between 18 and 60, more than 80 per cent of whom were given the vaccine, demonstrated a strong immunity to the effects of H5N1.

Glaxo said that this was a "significant breakthrough" and now hopes the treatment could be available for commercial use as soon as next year.

Glaxo's confidence about developing an H5N1 vaccine came as profits for the first half of the year roared ahead by 21 per cent to more than £4 billion on a 13 per cent leap in turnover to more than £11.6 billion.

Jean-Pierre Garner, the chief executive, upgraded Glaxo's guidance on annual earnings growth to about 12 per cent per share, in part prompted by a 10 per cent growth in pharmaceutical sales.

M Garnier also hailed the success of the vaccine trials as marking "real progress in our aspiration to develop a vaccine for use in preparing for an influenza pandemic".

The success of the trials appears to put Glaxo ahead in the race to produce a vaccine.

In May, Sanofi reported strong immune responses with a 30 microgram dose of its own treatment. However, when the level of active ingredient in the vaccine, or antigen, was reduce to 7.5 micrograms, the success rate dropped to 40 per cent.

However, another drugs rival, Baxter International, in February won the contract from the NHS for two million doses of its vaccine treatment for "key" public service workers.

Glaxo, like rivals Sanofi of France and Novartis of Germany, has been racing to develop an effective vaccine as a treatment for humans. Central to their efforts has been producing the maximum number of shots of a vaccine but with the minimum amount of antigen.

Glaxo said analysis of its clinical trials, which were carried out in Belgium, had shown a significantly high immune response among the participants, despite the vaccine containing a low amount of antigen.

The deadly N5N1 flu strain, which originated in Asia but has since spread rapidly, has already killed 130 people who have come into contact with infected birds.

Experts, including the World Health Organisation, fear that if its spread is not contained there could be a worldwide human flu pandemic that would see millions die.

The first company to produce a treatment available commercially stands to generate big profits because of the interest among governments in stockpiling H5N1 vaccines

Glaxo said the trials represented the first time that a vaccine containing such a low dose has been able to generate such a high immunity. It expects to file to health regulators for approval to begin manufacturing the drug over the coming months. If successful the treatment could be available in 2007.

Jean-Pierre Garnier, Glaxo's chief executive, said: "There is still a lot more work to be done with this programme, but this validation of our approach provides us with the confidence to continue developing the vaccine, including assessment of its ability to offer cross-protection to variants of the H5N1 strain.

"All being well we expect to make regulatory filings for the vaccine in the coming months."

The promising results of the trials either met or surpassed target criteria set by regulators to gain the approval needed for production of an H5N1 drug.

During the trials, participants were twice injected with the vaccine, which stimulates the body's immune system. Four different levels of antigen were used, with 3.8 micrograms being the lowest.

Shares of Glaxo gained 19p to 1549p in early trading.

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