Truvada, a retroviral drug combination in use for two years to treat people already infected with HIV, has been revealed to cut transmission of new infections in HIV-negative men by 44 percent, according to a new study:

"Daily doses of Truvada cut the risk of infection by 44 percent when given with condoms, counseling and other prevention services. Men who took their pills most faithfully had even more protection, up to 73 percent. Researchers had feared the pills might give a false sense of security and make men less likely to use condoms or to limit their partners, but the opposite happened — risky sex declined. The results are "a major advance" that can help curb the epidemic in gay men, said Dr. Kevin Fenton, AIDS prevention chief at the U.S. Centers for Disease Control and Prevention. But he warned they may not apply to people exposed to HIV through male-female sex, drug use or other ways. Studies in those groups are under way now. 'This is a great day in the fight against AIDS … a major milestone,' said a statment from Mitchell Warren, head of the AIDS Vaccine Advocacy Coalition, a nonprofit group that works on HIV prevention. Because Truvada is already on the market, the CDC is rushing to develop guidelines for doctors using it for HIV prevention, and urged people to wait until those are ready."

amfAR welcomed the results:

“Today marks a major step forward in our quest to combat HIV among MSM and other populations,” said amfAR CEO Kevin Robert Frost. “These results suggest that PrEP could be a very important prevention tool for gay men and MSM when used in combination with other prevention interventions including condoms. The findings underscore the tremendous return on investments in AIDS research, and the need for additional research to learn more about safety issues, whether PrEP could be protective in other populations, and the potential for intermittent use of PrEP.”