Two studies released Wednesday show that taking a daily pill containing an anti-HIV drug slashes infection rates. The studies provide further evidence that modern antiretroviral drugs can not only treat AIDS but also help prevent it.
One study's results were so dramatic, the study was halted and the drugs were given to all the participants because it was unethical to continue distributing placebos.
Since there is no vaccine that prevents the virus, this new approach, called pre-exposure prophylaxis (PrEP), could be one of the best bets for slowing the spread of one of the worst epidemics in modern times.
Although the studies confirmed earlier research, released last November, showing that PrEP could help prevent HIV infection in gay men, these studies were the first to show that heterosexual men and women could also benefit from a similar regimen.
In the first study, conducted by the U.S. Centers for Disease Control and Prevention (CDC) with the Botswana Ministry of Health, taking antiretroviral drugs cut the risk of HIV infection by 63% compared to a placebo among 1,200 sexually active men and women. They took tenofovir disoproxil fumarate and emitricitabine (TDF/FTC), whose brand name is Truvada.
In the other study (pdf), by the University of Washington and the Bill and Melinda Gates Foundation, transmission dropped 73% among nearly 5,000 heterosexual couples in which one partner had HIV and the other didn't.
Dr. Jared Baeten, the principal investigator of the Partners PrEP study at the University of Washington, told CNN:
"Just a few years ago the tool kit for HIV prevention was not very large. Now we have a nice collection of really powerful strategies that work for the population at greatest risk in the world. This is really a game changer."
Until a few years ago, the only methods known to help prevent HIV infection were using condoms and abstinence.
Kevin Fenton, director of the National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention at the CDC, told Time:
"As we think about the complexities of the domestic epidemic as well as the global epidemic, it's clear that we don't find one magic pill to solve the issue of HIV. But combining this prevention strategy with effective condom and other risk reduction strategies, we can now begin to get a better handle on the effective combination of packages that can be used against the virus."
Another reason it may not be enough to use PrEP alone is that it's not easy to guarantee that everyone will take their medications regularly. Indeed, in a study earlier this year that involved providing PrEP to commercial sex workers in Kenya, Tanzania and South Africa, those taking Truvada did not lower their risk of HIV infection compared to the placebo group, likely for that reason.
Gilead Sciences, the maker of Truvada and Viread, announced on Tuesday that it would license its anti-HIV drugs to an international organization, the Medicines Patent Pool Foundation, which aims to bring medicines at low cost to poor countries.
The CDC's next step is to fully analyze the data and develop guidelines over the next few months for the use of these drugs in heterosexual men and women in the U.S.
Photo: By Amada44 via Wikimedia Commons