 This is the VOA Special English Health Report. The journal Science chose an AIDS study as the 2011 breakthrough of the year. The study found that antiretroviral drugs can greatly lower the risk of spreading HIV, the virus that causes AIDS. It showed that infected people with early treatment were 96% less likely to infect their partners. The study was a clinical trial known as HPTN052. Myron Cohen led an international team that began the study in 2007. But Dr. Cohen says the work really began 20 years ago. We had a strong suspicion based on all the biological studies we had done that when we treat people and lower the concentration of HIV in the blood and secretions, we were rendering them less contagious. But we didn't understand the magnitude of the benefit. Dr. Cohen heads the Institute for Global Health and Infectious Diseases at the University of North Carolina at Chapel Hill. The National Institute of Allergy and Infectious Diseases paid for the study. It involved heterosexual couples in nine countries in Africa, Asia and the Americas. The results have already had an effect on government policies. Those changes include treating HIV infected people when their immune systems are still relatively healthy. Dr. Cohen says the study has generated policy changes at the level of the United States and the World Health Organization and UN AIDS. And it's inspired new community-based clinical trials that are just about to be launched that apply the scientific discovery. He says the results will be wasted unless they are linked to other areas of HIV testing, treatment and prevention. If we don't know who's positive and negative, there's no benefit. If people aren't linked to care, there's no benefit. If they aren't provided drugs, there's no benefit. If they receive the drugs but don't take the pills, there's no benefit. So this cascade is now the focus of our attention. AIDS activist Mitchell Warren says, For many years, debates have waged whether we should do treatment or prevention. The results of the HPTN052 study actually affirm once and for all that treatment is prevention. The journal Science also recognized nine other achievements. These include progress on a malaria vaccine and research on the DNA of our ancient ancestors. Another study looked at cells that have stopped dividing. It found that clearing them from the bodies of mice can delay some of the effects of aging. A link to the full list is at voaspecialenglish.com. For VOA Special English, I'm Alex Villareal.