July 13, 2011 -- In what researchers are calling a major breakthrough in HIV prevention, the findings released today from two studies in Africa show encouraging results in the reduction of HIV transmission among heterosexuals. Both studies reveal that an uninfected person can significantly reduce the risk of acquiring the infection by taking medicine used to treat AIDS.
In one study called TDF2, the Centers for Disease Control (CDC) followed more than 1,200 HIV-negative sexually active men and women in Botswana – a country with a population hard hit by HIV. In the trial, half of the participants were either given a daily dose of Truvada (TDF/FTC), used to treat HIV-positive individuals, or a placebo pill.
Results show that those who took the HIV medication dramatically reduced their risk of acquiring the infection--by 62 percent.
This prevention strategy in which an HIV-negative person takes antiretroviral medication (ARV) daily to lower the chances of becoming infected is called pre-exposure prophylaxis, or PrEP.
In a separate clinical trial called "Partners PrEP", the University of Washington followed close to 5,000 couples in Kenya and Uganda where one partner was HIV-positive and the other was not. The uninfected partners were either given the HIV medicine Tenofovir, a combination of TDF/FTC, or a placebo pill.
Those who took the TDF/FTC combination had 73 percent fewer HIV infections compared to 62 percent for the group that took Tenofovir.
Dr. Jonathan Mermin, director of the HIV/AIDS Prevention Division for CDC, said today: "It's a breakthrough in prevention…Up to this point, we have not had the opportunity to prevent acquisition among unaffected people."
This year marks 30 years of the HIV/AIDS epidemic. According to UNAIDS, more than to 34 million people are living with HIV worldwide; two-thirds of them in sub-Saharan Africa. While there is no single magic pill to solve the problem of HIV, the combination of these studies show advancement in effective preventive measures.
"These are exciting results for global HIV prevention," said Dr. Kevin Fenton, director of CDC's National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention. "Taken together, these studies provide strong evidence of the power of this prevention strategy."
Dr. Jared Baeten of the University of Washington led the "Partners PrEP" study conducted in Kenya and Uganda. "Just a few years ago, the toolkit for HIV prevention was not so large," he said. "Now we have a nice collection of really powerful strategies that work for the population with the greatest need in the world."
The full results from the "Partners PrEP" and TDF2 studies will be discussed and presented at the 6th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention in Rome next week.