Race Affects Test Aids Vaccine

An experimental Aids vaccine being developed by VaxGen does not appear to protect most people from the disease but does show promise in protecting black people and Asians, the company said last night.

Long-awaited results from the first-ever trial of a vaccine against HIV infection showed it only reduced the rate of infection by 3.8% in 5,400 men and women considered at high risk, VaxGen said in a statement.

However, the expected infection rate for the 314 black volunteers who received the vaccine was reduced by 78% - a finding the researchers said was unexpected. The rate was reduced by 67% for all non-white volunteers other than Hispanics.

The VaxGen vice-president, Phillip Berman, said: "This is the first time we have specific numbers to suggest that a vaccine has prevented HIV infection in humans ... we're not sure yet why certain groups have a better immune response."

The company, which is based in Brisbane, California, said it planned to continue developing the vaccine and will examine more closely why it worked better with black people and Asians than it did with in whites and Hispanics.

The experiment, which initially involved 5,400 people at high-risk for the disease, had been criticised by some activists who said it could encourage risky behavior. Even if the vaccine proved effective on some people, there might be no way to tell if it had worked on a particular individual.

However, VaxGen has won widespread praise from doctors and the US food and drug administration for its handling of an ethically difficult test. The company counseled patients in the experiments to practice safe sex because the vaccine might not work and because one-third of the volunteers received the placebo.

The publicly traded company's stock has risen and fallen dramatically during the last year as rumours of the experiment's results swirled. It sold for as low as $4.81 (£3.05) a share and as high as $23.25. It closed at $13.02 in trading on the Nasdaq stock market on Friday.

Experts believe a vaccine is the only way to stop the worldwide Aids epidemic, which has already killed 20 million people and infected 40 million more.

A different firm, Merck & Co, is developing a vaccine that showed promise in early human testing but researchers said they were still years away from proving whether it works.