That was fast. Two weeks after the last widely reported breakthrough against HIV, here comes another one.

Researchers in South Africa and the United States conducted a study involving 900 HIV-uninfected South African women with a gel containing tenofovir, an antiretroviral drug. The gel prevents the virus from multiplying. It was determined that women who use the gel reduce their infection risk by 50 percent after a year.

In the study, half of the women received the gel, the other half received a placebo.

The study was published in the journal Science and will be presented at today's International AIDS Conference in Vienna, Austria.