As poor cities continue to struggle with AIDS, good news is afoot on the drug-research front: A new vaginal gel containing the antiretroviral drug tenofovir can cut the risk of acquiring the virus for women. In a study of 900 South African women, the gel cut the rate of infection by 39 percent; if used consistently, the result jumped to 54 percent. “We have never had any kind of tool that has effectively allowed women to protect themselves,” Bruce Walker, an AIDS researcher at Harvard Medical School, told The Washington Post. “This is really a game changer.” Worldwide, 16 million women are infected with AIDS, and 60 percent of those infected in Africa are female. In the 15-year search to find a protection method, six other microbicides were tested in 11 clinical trials, but nothing proved to work. This gel marks the first method of female-controlled HIV protection.