Experimental HIV vaccine cuts infection

An experimental HIV vaccine has, for the first time, cut the risk of infection, researchers say. The vaccine - a combination of two earlier experimental vaccines - was given to 16,000 people in Thailand, in the largest ever such vaccine trial.

"It is the first demonstration that a vaccine against HIV can protect against infection," Colonel Jerome Kim of the US military HIV research program told a news conference in Bangkok via videolink. "This is a very important scientific advance and gives us hope that a globally,' he added.

Based on Sanofi and VaxGen older vaccines

The Phase III clinical trial, involving more than 16,000 adult volunteers in Thailand, found that it was safe and modestly effective in preventing HIV infection, according to French drug major Sanofi-Aventis, which makes the Alvac HIV vaccine that was used in combination with the AidsVax B/E vaccine developed by VaxGen and now licensed to the non-profit Global Solutions for Infectious Diseases.

"This is the first concrete evidence, since the discovery of the virus in 1983, that a vaccine against HIV is eventually feasible," said Michel DeWilde, R&D senior vice president for Sanofi Pasteur, the vaccines division of Sanofi-Aventis.
Michael Leacock, an analyst at the Royal Bank of Scotland quoted by MarketWatch, said the study suggests a "prime-boost" strategy could be effective but noted that the vaccine isn't successful enough for licensing. "We see no commercial vaccine available for some time yet, but the prospect has finally been raised - after around 30 years of trying - that an effective vaccine is possible," he said.

Researchers found that the vaccine reduced by nearly a third the risk of contracting HIV, the virus that leads to AIDS. It has been hailed as a significant, scientific breakthrough, but a global vaccine is still some way off.

The study was carried out by the US army and the Thai government over seven years on volunteers - all HIV-negative men and women aged between 18 and 30 - in some of Thailand's most badly-affected regions. The vaccine was a combination of two older vaccines that on their own had not cut infection rates.

Half of the volunteers were given the vaccine, while the other half were given a placebo - and all were given counselling on HIV/Aids prevention. Participants were tested for HIV infection every six months for three years. The results found that the chances of catching HIV were 31.2% less for those who had taken the vaccine - with 74 people who did not get the vaccine infected and 51
of the vaccinated group infected.

'Encouraging' results

"This result is tantalizingly encouraging. The numbers are small and the difference may have been due to chance, but this finding is the first positive news in the Aids vaccine field for a decade," said Dr Richard Horton, editor of the Lancet medical journal, adding: "We should be cautious, but hopeful. The discovery needs urgent replication and investigation."

Anthony Fauci, Director of the US National Institute of Allergy and Infectious Diseases said: "For the first time, an investigational HIV vaccine has demonstrated some ability to prevent HIV infection among vaccinated individuals. Additional research is needed to better understand how this vaccine regimen reduced the risk of HIV infection, but this is certainly an encouraging advance for the HIV vaccine field."

The findings were also hailed by the World Health Organization and the Joint United Nations Programme on HIV/Aids (UN/Aids) which said while the results were "characterized as modestly protective... [they] have instilled new hope in the HIV vaccine research field."