Two new studies show that drugs designed to treat HIV can also help prevent people from contracting the virus, which causes AIDS.
The U.S.-led studies, released Wednesday, found that taking daily doses of HIV medication reduced the risk of infection in heterosexuals.
Both of the studies were conducted in Africa, home to most of the world's HIV-infected people.
The U.S. Centers for Disease Control and Prevention ran one of the new trials, which involved more than 1,200 uninfected men and women in Botswana. About half were given the treatment, while the other half received a placebo pill.
The study found the medication reduced the risk of infection by 78 percent among those believed to be regularly taking it.
The second study was led by the University of Washington and funded by the Bill & Melinda Gates Foundation. It involved more than 4,700 heterosexual couples in Kenya and Uganda. In each couple, one partner had HIV and the other did not. The uninfected were given either daily placebos or one of two different kinds of treatments.
The researchers said the medications reduced the risk of HIV infection by 62 percent to 73 percent.
The director of the CDC's national center for preventing HIV/AIDS and other infections called the findings “exciting results for global HIV prevention.” He said the two studies provide strong evidence of the power of the pre-exposure prevention strategy.
A previous study had already shown treatment reduced HIV transmission among gay men. But these new findings were the first to show a daily oral dose of antiretroviral drugs is effective among heterosexuals.
