In 2005, a group of researchers set out to prove that starting antiretrovirals in the early stages of HIV can prevent the transmission of the diseases. They just released results of the trial a full ten years earlier than originally intended due to how positive the outcome has been.

In a study of 1,763 mostly heterosexual couples from nine countries in which one of the partners had contracted HIV, researchers separated the participants into two groups at random. One group waited until they got an AIDS-related illness or their CD4 T-cell count dropped below 250 (HIV negative count should be 600-1200) to begin antiretrovirals. The other began taking antiretroviral medications immediately.

Lead researcher Dr. Myron Cohen, director of the Institute for Global Health and Infectious Diseases at the University of North Carolina at Chapel Hill, says the research showed exactly what they thought it would. Thirty-nine new infections were detected. Twenty-eight of them were genetically proven to have come from the partner in the study. And 27 of those were people who waited to begin the antiretrovirals.

But Cohen says the findings don't apply to all HIV-positive people. “Our couples had big advantages,” he said. “We enrolled couples who probably have a low overall transmission [HIV] rate,” he said.