Washington: In a breakthrough, researchers have for the first time found a vaccine that cuts HIV infection by more than 31 per cent, giving fresh boost to the global fight against the dreaded disease.

The experimental drug has cut the risk of HIV infection by a third in the world’s largest AIDS trial of more than 16,000 volunteers in Thailand, researchers said.

It is the first time after two decades of human trials that a vaccine has stopped the HIV virus, which infects 7,500 across the globe every day.

“It gives me cautious optimism about the possibility of improving this result and developing a more effective AIDS vaccine”, Anthony Fauci, director of the United States National Institute of Allergy and Infectious Diseases was quoted by Washington Post.

Colonel Jerome Kim, who led the study for the US Army as part of the trial, said, “It is the first evidence that we could have a safe and effective preventive vaccine.”

The vaccine, a complicated mixture of six “prime” and “booster” shots, is the first positive result after two decades of experimentation, the newspaper said.

“Conceptually, we now know a vaccine is possible,” saidFauci, adding, “Whether the vaccine is going to look anything like this one I don’t know. But at least we know it can be done.”

The finding is statistically significant with 31.2 per cent effectiveness but scientists seldom consider licensing a vaccine which is less than 70 or 80 per cent effective.