BILL GATES, the Microsoft billionaire, dismissed the prospect yesterday of an Aids vaccine being discovered in the near future, saying he would “eat his hat” if it appeared within the next decade.

Mr Gates, the world’s biggest private donor to vaccine research, said that he would be very surprised if claims by Gordon Brown and other politicians of the imminent appearance of a vaccine came true. He was speaking a month after Mr Brown confidently asserted that if spending on research was doubled in coming years, a preventative vaccine for HIV could be available as early as 2012.

The Chancellor has committed £1.4 billion of government funds to such research over the next decade, and he hopes to set up a funding scheme that will provide £100 billion towards Aids treatment by 2015.

Describing the hunt for an Aids vaccine as the world’s most testing scientific problem, Mr Gates sounded a note of caution on overselling the chances of success. “If you took a poll of reputable scientists they would say that it (an Aids vaccine) is further away today than they would have said even ten years ago,” he said. “It is not a question that we have not made progress in that time. It’s just that all the simple things didn’t work and even the quite non-simple things didn’t work.” Asked if Gordon Brown’s target would be met, he replied: “I would be happily, happily surprised. I would eat my hat.” Speaking shortly before his visit to Buckingham Palace, where he received the insignia of an honorary knighthood from the Queen, Mr Gates said that an Aids vaccine remained the single most important challenge for his £17 billion charitable foundation. “An Aids vaccine is not around the corner. We are just going to keep funding until there is one,” he said.

“We will have a vaccine sooner if governments like the UK are willing to contribute to the vaccine enterprise. It’s exemplary, it’s fantastic, to be willing to make that investment now.”

In January he announced a £400 million donation to vaccine research by the Bill and Melinda Gates Foundation, matching the donation it made in 2000. Aids is currently the world’s biggest killer, claiming more than three millions lives in 2003 and taking the total death toll since the early 1980s to more than 20 million.

With a further five million people being found to be HIV-positive during the year, almost 40 million people now carry the virus.

Since the couple visited Africa in 1993, Mr and Mrs Gates have become the world’s most powerful supporters of projects which combat disease in developing countries.

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