25 September 2009

Aids vaccine: a breakthrough

A new Aids vaccine that cuts the risk of HIV infection by a third is "historic" and the most important advance in HIV vaccine research to date, experts said Thursday.

A new Aids vaccine that cuts the risk of HIV infection by a third is "historic" and the most important advance in HIV vaccine research to date, experts said Thursday. But the new drug needs to be more effective to counter the disease, which has killed 25 million people around the world since it first appeared in 1981, they said.

The World Health Organisation (WHO) and the Joint UN Programme on HIV/Aids called the Thai-US researchers' work a "significant scientific advance."

"These results have instilled new hope in the HIV vaccine research field, and promise that a safe and highly effective HIV vaccine may become available for populations throughout the world who are most in need of such a vaccine," the UN organs said. "This is a historic day in the 26-year quest to develop an Aids vaccine," said Alan Bernstein, executive director of the Global HIV Vaccine Enterprise, a global alliance of research groups, funders and pharmaceutical companies.

"The results of the Thai Phase III HIV vaccine clinical trial ... demonstrate that a safe and effective Aids vaccine is an achievable goal," he said in statement.

Cuts risk by 31%
The rapid identification of the Aids virus after the disease emerged in the early 1980s fueled optimism that a vaccine would quickly emerge. But none of the dozens of candidate drugs tested since then have worked until now.

Jean-Francois Delfraissy, Director of France's National Aids Research Agency, also hailed the "good news", but cautioned that the effects remain modest.

"We don't yet have a vaccine against HIV," he told AFP. A 31% reduction in the risk of infection "is insufficient by a wide margin. This is not a vaccine tool that can be used by public health services for the population at large," he said.

When deciding whether to license a vaccine, most national health authorities require that a vaccine of any type be at least 70% to 80% effective, according to experts. Delfraissy also pointed out that the "viral load" - the amount of virus in the blood - was the same among those who were infected despite having been vaccinated as in a control group given a placebo.

Reducing the viral load in those patients who were not protected by the vaccine was one of the explicit aims of the trial.

The new vaccine - a mix of two drugs that failed to impede infection on their own - was tested in Thailand in trials carried out by the US Army and the Thai Ministry of Public Health on more than 16,000 healthy adult men and women volunteers.

The results will help set the agenda for new research, experts said.

Platform to work from
"For more than 20 years now, vaccine trials have essentially been failures," said Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases (NIAID), one of the trial's backers.

"It's like we were groping down an unlit path, and a door has been opened. We can start asking some very important questions," he was quoted as saying by the New York Times.

Wayne Koff, vice president of the International Aids Vaccine Initiative, based in New York, said that "at the very least, these results give researchers a platform on which to improve and to validate animal models ... and attract new investment."

Grassroots groups said the breakthrough should be an incentive to intensify the search for a fully-effective vaccine. "We call on researchers, private funding organisations and public health authorities to step up financial and scientific efforts to find an anti-HIV vaccine," Paris-based AIDES said in a statement.

The study combined the canarypox vaccine ALVAC, manufactured by Sanofi-Aventis of France, and AIDSVAX, originally made by VaxGen Inc and now licensed to Global Solutions for Infectious Diseases.

Some 33 million people are living with Aids or the HIV virus. More than two-thirds of those live in sub-Saharan Africa. - (Sapa-AFP, September 2009)

Read more:
Aids vaccine a 'giant leap' for SA
HIV/Aids Centre


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