Taking daily antiretroviral drugs greatly cuts the chances of getting infected with AIDS, researchers have found in a groundbreaking new study.
The study published today in the New England Journal of Medicine, offered the first indication of an oral method to prevent the spread of HIV among those at high risk.
"This is an important trial that further extends the growing appreciation that antiretroviral therapy can play a vital role in controlling the HIV epidemic," said Dr. Paul Volberding, co-director of the University of California San Francisco Center for AIDS Research, who was not involved with the study.
The study, which began in June 2007, followed 2,499 men and transgendered women from six countries -- including the United States -- who engaged in sex with other men and were categorized as high risk for HIV infection. Participants were randomized to either receive a combination antiretroviral drug commonly known as Truvada or a placebo.
Participants assigned to Truvada who reported taking the daily pills about half of the time they were prescribed had about a 50 percent lower risk of getting HIV. Those who reported taking the medication about 90 percent of the time had a 73 percent lower risk of infection.
"We think our results can be generalized to all communities in the world," said Dr. Javier Lama, study co-chair from Investigaciones Medicas en Salud in Peru.
In 2008, over 42,000 people in the U.S. were diagnosed with HIV. Nearly half of those infected were men who engaged in sex with other men, according to the Centers for Disease Control and Prevention.
According to Dr. Tom Coates, director of the UCLA program in global health, condom use "has already decreased due to HIV treatment being so effective."
"HIV prevention is already not working all that well among gay men," Coates said.
Surprisingly, study participants who used the new oral method, called pre-exposure prophylaxis -- or PrEP -- reported a higher compliance with other HIV prevention methods such as condom use, and also reported a decrease in the number of sexual partners, said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, an arm of the National Institutes of Health in Bethesda, Md., which partly funded the study.
While preventative antiretroviral therapy is an innovative method, it's likely to be only a part of the larger HIV prevention effort, he said.
In fact, all study participants received additional HIV prevention, including condoms, counseling, as well as periodic HIV testing. However, the rise in HIV infections is due in large part to the failure of high-risk groups to use prevention methods.
Dr. Robert Grant, study chair from Gladstone Institute of Virology and Immunology at the University of California San Francisco warned self-reported use of medication often proves to be higher than actual use.
In fact, Grant said one of the challenges of oral PrEP may be that some may find it difficult to take the pill daily.
"Finding ways to support use of daily pill is focus of [the] next studies," said Grant, adding that future studies should determine whether more limited and shorter term use of the pill, along with other available prevention methods, may prove just as effective.
"Sustainability of treatment programs requires that something needs to be done to decrease infection [rates]," Grant said.