Daily intake of AIDS drugs slashes HIV infection risk - report

Two studies conducted in Africa have shown for the first time on Wednesday that AIDS drugs designed to treat HIV can also be used to reduce dramatically the risk of infection among heterosexual couples.

The findings add to growing evidence that the type of medicines prescribed since the mid-1990s to treat people who are already sick may also hold the key to slowing or even halting the spread of the sexually transmitted disease.

The research involving couples in Kenya, Uganda and Botswana found that giving daily AIDS drugs reduced infection rates by an average of at least 62 per cent when compared with placebo.

The findings were contained in a statement by the director-general of the World Health Organization (WHO), Margaret Chan.

The statement says “effective new HIV prevention tools are urgently needed and these studies could have enormous impact in preventing heterosexual transmission.”

Better protection strategy

In an indication of the importance of the latest evidence, Chan said the United Nations health agency would now work with countries to use the new findings to implement better protection strategies.

The larger of the two studies examined 4,758 couples in Kenya and Uganda in which one partner was HIV-positive and one was negative. Those negative partners taking Gilead Sciences Inc's tenofovir, or Viread, had on average 62 percent fewer infections.

For couples on Truvada -- another Gilead drug combining tenofovir and emtricitabine -- the infection risk was cut by an estimated 73 percent in the clinical trial, which was led by researchers at the University of Washington.

The study was funded by the Bill & Melinda Gates Foundation, whose director of HIV and Tuberculosis, Stefano Bertozzi, said it marked "a significant milestone in the quest to develop new HIV prevention measures".

The second study, involving just over 1,200 sexually active men and women in Botswana, found those on daily Truvada reduced their risk of HIV infection by 62.6 percent.

The idea of such "pre-exposure prophylaxis", known as PrEP, has gained traction in the past year, following results of other research showing a fall in infection rates among gay men taking AIDS drugs.

However, PrEP took a knock earlier this year when another study failed to demonstrate a protective effect in high-risk women. The latest strong evidence is likely to restore confidence in the approach.

Fight against spread of HIV

Around 33 million people worldwide have the human immunodeficiency virus (HIV) that causes AIDS, most living in Africa and Asia. Only about half know their HIV status, and the WHO hopes that news of an effective approach to prevention will encourage more people to get tested.

The Head of the UN's programme on HIV/AIDS, Michel Sidibe, said the new studies could help reach the tipping point in the HIV epidemic.

The larger study, conducted in Kenya and Uganda, had been scheduled to run until late 2012 but it was stopped early because the evidence of efficacy was so strong.

Results of the Botswana study, led by the US Centers for Disease Control and Prevention, had been due to be unveiled next week at an international AIDS congress in Rome but were released ahead of time to coincide with the University of Washington research.

According to the WHO, “the PrEP approach of using just one daily pill is much more convenient -- and the drugs are available as generics in many poor countries at prices as low as 25 US cents a tablet”.

Prices could fall further and supplies increase following an agreement by Gilead, the leading maker of HIV drugs, to share intellectual property rights on its medicines in a new patent pool.

The California-based group on Tuesday became the first drug maker to sign up to the Medicines Patent Pool.

REUTERS/Williams