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Friday, September 25, 2009

HIV vaccine hailed as 'historic milestone' in fight against Aids

A vaccine has reduced the chance of HIV infection in humans for the first time, in what the scientific community has hailed a breakthrough in the fight against Aids.

HIV virus particles: Aids breakthrough: vaccine prevents HIV infection for first time
HIV virus particles Photo: GETTY IMAGES

The combination of two vaccines that has previously failed to produce a response on their own has cut the risk of becoming infected with HIV by more than 31 per cent.

It is the first time in human trials that a vaccine has protected against the virus which leads to Aids.

The trial was conducted in 16,000 volunteers in Thailand, with half receiving the combination of the two vaccines and the other half receiving dummy jabs.

Dr. Anthony Fauci, director of the United States National Institute of Allergy and Infectious Diseases, warned the development was "not the end of the road," but said he was surprised and very pleased by the outcome.

"It gives me cautious optimism about the possibility of improving this result" and developing a more effective Aids vaccine, he said. "This is something that we can do."

The trial was carried out by the U.S. Military HIV Research Program and the Thai Ministry of Public Health.

Seth Berkley, chief executive and president of The International Aids Vaccine Initiative (IAVI) said: “The outcome is very exciting news and a significant scientific achievement.

“It’s the first demonstration that a candidate Aids vaccine provides benefit in humans. Until now, we’ve had evidence of feasibility for an AIDS vaccine in animal models. Now, we’ve got a vaccine candidate that appears to show a protective effect in humans, albeit partially.”

The challenge will now to be improve the efficiacy of the vaccines to a level which clear protection so it can be licensed for widespread use.

Deborah Jack, Chief Executive of the National Aids Trust, said: "These vaccine trial results are very good news - ultimately vaccines are the most effective way by far of tackling serious infectious disease. And with over two million new HIV infections a year this option is desperately needed.

"Obviously there is much more work to do with these promising findings, but they justify the continuing investments and efforts of the international community, including the UK Government, to develop a vaccine."

Wayne Koff, IAVI Senior Vice President for Research and Development, said: “At the very least, these results give researchers a platform on which to improve and to validate animal models and assays, and a way to attract new investment and creative energy to the field of Aids vaccine R&D.”

"Today marks a historic milestone," said Mitchell Warren, executive director of the Aids Vaccine Advocacy Coalition, an international group that has worked toward developing a vaccine.

"It will take time and resources to fully analyse and understand the data, but there is little doubt that this finding will energise and redirect the Aids vaccine field.

Even a partially effective vaccine could have a big impact. In 2007, two million died of Aids according to the United Nations agency UNAIDS.

Colonel Jerome Kim, who helped lead the study for the US Army, which was also involved in the trial, said: "It is the first evidence that we could have a safe and effective preventive vaccine."

The Thailand Ministry of Public Health conducted the study, which used strains of HIV common in Thailand. Scientists stressed it is not clear whether the vaccine would work against other strains in the United States, Africa or elsewhere.

The study tested a two-vaccine combination where the first injection primes the immune system to attack HIV and the second strengthens the response.

The vaccines are ALVAC, from Sanofi Pasteur, the vaccine division of French drugmaker Sanofi-Aventis; and AIDSVAX, originally developed by VaxGen Inc. and now held by Global Solutions for Infectious Diseases, a non-profit founded by some former VaxGen employees.

All the participants tested negative at the start of the trial and were given condoms, counselling and treatment for any sexually transmitted infections. They were tested every six months for HIV and any who became infected were given free treatment with antiviral medicines.

Participants were followed for three years after vaccination ended.

The results were that new infections occurred in 51 of the 8,197 given vaccine and in 74 of the 8,198 who received dummy shots. That worked out to a 31 per cent lower risk of infection for the vaccine group.

The vaccine had no effect on levels of HIV in the blood of those who did become infected, providing "one of the most important and intriguing findings" of the trial, according to Dr Fauci, giving scientists important clues in identifying whether treatment drugs actually make a difference by giving protection to the immune system.

The researchers have been careful to say the vaccine combination appears to have an effect on the HIV strain circulating in Thailand and it may not work on other strains elsewhere in the world.

Full details of the $105 million study will be given at a vaccine conference in Paris in October.