South African women who used a vaginal gel infused with the antiretroviral drug tenofovir reduced their likelihood of getting the disease by about 50 percent, according to a two-year study published today in the journal Science.

The finding comes after 20 years of searching for an effective microbicidal gel and a number of failed clinical trials. The benefit of a vaginal gel over condoms is that it puts women in control of protecting themselves, rather than requiring a man’s permission. About 60 percent of new HIV infections in Africa are in women and girls.

According to an article in the New York Times;

Bruce Walker, a Harvard Medical School professor who was not involved in the study, said a cheer erupted when researchers unveiled their findings to a small group of scientists last month in Durban. “This is the first time that there’s been a tool that women can use to protect themselves from becoming infected,” he said. “It’s a game changer.”

[…] The women who participated in the study – in the city of Durban and in the rural community of Vulindlela, in the rolling hills of KwaZulu-Natal – used a the gel up to 12 hours before and after sex. Usually their partners were not aware of it. Tissue biopsies found levels of tenofovir that were 1,000 times higher than they would have been in the blood if the drug had been taken by pill, the team said.

Researchers will next evaluate the gel’s safety over the longer term. Scientists are also exploring whether giving the drug in pill form prior to exposure can reduce infection more effectively.