Britain said on Friday it was ordering around 3.5 million doses of H5N1 bird flu vaccine from manufacturers Baxter International Inc. and Chiron Corp.

British Health Minister Rosie Winterton said the contracts were worth 33 million pounds ($57.7 million) and were part of efforts to prepare for and reduce the impact of a possible flu pandemic.

In a separate statement, Baxter said it would supply two million doses of its vaccine against avian flu which is still under development.

The British Department of Health said the vaccine was scheduled for delivery in May and October 2006 and added it would be used for further research and could be used to vaccinate healthcare workers before a specific pandemic flu vaccine can be developed.

Bird flu has killed more than 90 people around the world, but it remains essentially an animal disease which people contract only through direct contact with infected birds.

Experts fear it is only a matter of time before it changes into a form that passes easily between humans, sparking a pandemic in which millions could die.

Britain’s only reported case of the virus came at a quarantine centre last year, but it is creeping closer with cases confirmed in wild birds in France and Germany.

Noel Barrett, vice president of vaccines at Baxter International, told reporters the vaccine was based on a strain of H5N1 found in Vietnam in 2004. Vietnam has reported 42 deaths from the virus.

However, he said it was not clear whether this vaccine would offer any protection should a mutated pandemic strain emerge.

Dr David Salisbury, head of immunisation at the Department of Health, said the order was part of British efforts to prepare thoroughly for the threat of avian flu.

“What we have done is to put orders for a second-generation vaccine, that is a slightly more powerful vaccine so that you can use smaller doses to make it go further and also with the hope that it will give broader protection should the virus change,” he told Sky News.

Barrett said Baxter’s cell-based vaccine production system was more rapid than traditional methods using chicken eggs.

“We’ve calculated we could have first batch of vaccine available 11 weeks after receipt of a pandemic strain ... which is probably about three months earlier than can be achieved using standard technology involving use of the egg,” he said.

Britain said the order was in addition to plans for so-called sleeping contracts for 120 million doses of a pandemic vaccine. Sleeping contracts are a way of reserving future access to vaccine supplies.

California-based Chiron is being bought out by Novartis AG of Switzerland.