Could a vaccine for HIV be on the horizon?

HIV Vaccine

US military-backed medical trials in Thailand have revealed the first evidence of a possible vaccine against HIV, where tests have allegedly cut infection rates by a third.

Last month, clinical trials saw more than 16,000 adult volunteers in Thailand receive a prime-boost HIV vaccine. Results revealed that the vaccine was not only safe, but had lowered the rate of HIV infection by 31.2 percent compared to placebo.

The study used strains of HIV common in Thailand and tested the two-vaccine combination in what's called a "prime-boost" approach. The first vaccine primes the immune system to attack HIV, whilst the second one strengthens the response. The two vaccines are called ALVAC and AIDSVAX.

ALVAC contains canarypox, which is a bird virus that has been genetically altered so it can't cause disease in humans. It is used to transport synthetic versions of three HIV genes into the body. AIDSVAX, on the other hand, contains a genetically engineered version of a protein on HIV's surface. Because the vaccines aren't made from a whole virus - either dead or alive - they can't cause AIDS in trial subjects.

The trial was held in Thailand because US Army scientists have been doing key research there, ever since the AIDS epidemic emerged there. Their work has seen them isolating virus strains and providing genetic information on them to vaccine makers, whilst receiving support from the Thai government.

Colonel Jerome Kim, who helped to lead the $105m study for the US army, told UK newspaper The Guardian, that it was "the first evidence that we could have a safe and effective preventive vaccine".

The trial was the largest ever conducted, and despite the relatively modest success rate of 31.2 percent, it has been hailed as a milestone advance in finding a cure.

"I don't want to use a word like 'breakthrough,' but I don't think there's any doubt that this is a very important result," Dr. Anthony S. Fauci, director of the US National Institute of Allergy and Infectious Diseases, one of the trial's sponsors.

"For more than 20 years now, vaccine trials have essentially been failures," he said. "Now it's like we were groping down an unlit path, and a door has been opened. We can start asking some very important questions."

However some have dismissed the results saying that the data "may be even weaker than the authors admitted." Paul E. Sax, MD, clinical director of the HIV Program and Division of Infectious Diseases at Brigham and Women's Hospital and associate professor of medicine at Harvard Medical School in Boston, Massachusetts, told Medscape HIV/AIDS, "We'll have to hope there's more clarity when the study results are presented in a scientific conference and (even better), published in a peer-reviewed journal."

He also blogged that, "Researchers from the US Army and Thailand announced last month they had found the first vaccine that provided some protection against HIV. But a second analysis of the $105 million study, not disclosed publicly, suggests the results may have been a fluke, according to AIDS scientists who have seen it." Sax is not alone. Some critics have said that the vaccine's efficiency may not be 31 percent as claimed, but closer to 26 percent.

Since the HIV/AIDS virus struck over a quarter century ago, it has killed an estimated 32 million people. In 2007, 33 million people around the world were living with HIV/AIDS. More than 64.9 million people have been infected with HIV since the pandemic began. AIDS is the leading cause of death in sub-Saharan Africa, and the fourth leading cause of death globally, according to the US Agency for International Development.

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