HIV Drug Reduces Transmission Among Men By Over 40%, Study Finds

A daily dose of antiretroviral medication lowered the risk of contracting HIV by more than 40% among men who have sex with men, according to a study published Tuesday in the New England Journal of Medicine, the New York Times reports.

The results of the study -- nicknamed iPrEx -- "are the best news in the AIDS field in years" and "could change the battle" against HIV/AIDS, according to the Times . Experts suspect the medication will be successful in other groups but caution that it must be tested first.

Details of Study

An international team of researchers enrolled 2,499 MSM at 11 sites in six countries to test a prevention strategy known as pre-exposure prophylaxis, which has been successful in preventing other diseases. The team was led by Robert Grant of the University of California-San Francisco Gladstone Institute of Virology and Immunology and Javier Lama of the Investigaciones Medicas en Salud in Lima, Peru . NIH and the Bill and Melinda Gates Foundation funded the study .

Half of the participants received a daily dose of Truvada, an antiretroviral drug containing emtricitabine and tenofovir, while the other half received a placebo. Both groups received counseling about condom use and safer sex practices. The researchers found that 36 participants taking Truvada contracted HIV, compared with 64 in the placebo group, representing a 43.8% reduction. They noted that the decrease was dependent on how frequently the subjects took the medication. Those who adhered to their medication at least half of the time experienced a 50.2% decline in risk, while those who took their medication at least 90% of the time saw a 72.8% risk reduction .

Caveats to Strategy

The researchers noted several limitations to the study, including that it only involved MSM and one combination of antiretroviral drugs. They said additional studies are under way to test Truvada in other high-risk groups, such as commercial sex workers and intravenous drug users, and heterosexual men and women.

Some HIV/AIDS advocates and scientists expressed concern about the cost of the strategy. Truvada costs between $12,000 and $14,000 annually in the U.S. Generic versions in developing countries cost as little as 40 cents per pill. They said they are also concerned that placing people on the drugs will speed the evolution of drug resistant strains of the virus or that people will stop using condoms .

Kevin Fenton, AIDS prevention chief at the Centers for Disease Control and Prevention, said that prophylaxis "should never be seen as a first line of defense against HIV," adding, "It's not time for gay and bisexual men to throw out their condoms" .

Grant said that the findings are "a major advance," but the strategy "will only work if people use it consistently, and the real challenge is how do you use it consistently" .

Advances in Preventive Approach

The findings follow this year's success with a vaginal microbicide gel and a proof-of-concept trial on an HIV vaccine . The microbicide study indicated that the gel protected 39% of all women testing it and 54% of those who used it consistently .

Alan Bernstein, health of the Global HIV Vaccine Enterprise, said, "This is a very exciting, dynamic time in HIV prevention research," adding, "There's clearly a growing realization that we're not going to be able to treat our way out of this epidemic" .