Providing HIV-negative people in sub-Saharan Africa with an antiretroviral drug to protect them against HIV infection could prevent 3 million new cases of HIV over a 10-year period, according to findings from a new study reported in PLoS One, a journal of the Public Library of Science.

A drug used to treat HIV/AIDS, tenofovir (Viread), has been tested on monkeys, and has been shown to be effective in protecting them from the simian version of HIV. The drug is now being tested on humans to see if it can prevent the transmission of HIV to people. The results of the human trials will not be available until 2008.

Using a computer model to project how effective the drug could be in sub-Saharan Africa, where more than 22 million adults are already HIV positive, scientists have determined that if tenofovir proves to be an effective preventative measure and is given to the most sexually active individuals in the population, it could cut the infection rate by almost 30 percent over the course of a decade.