Daily Potent Pill Prevents Half of HIV Infections Among Intravenous Drug Users

A new drug is leading the way in preventing the spread of the HIV virus among drug users, after a test found that by taking a daily dose of the Gilead Sciences Inc.'s Viread pill, HIV infection rate among intravenous drug users in Thailand were cut by 49 percent.

More than 2,400 drug users in Bangkok were examined over a period of five years, and those who took Viread daily were 49 percent less likely to get infected with HIV than those who got a placebo, researchers from the Thai Ministry of Public Health and the U.S. Centers for Disease Control and Prevention reported Wednesday in the Lancet.

The study found that addicts, who took the pills regularly, based on measures of tenofovir in their blood, did much better as they were 74 percent less likely to become infected.

"This is a significant step forward for HIV prevention," said Dr. Jonathan Mermin, director of the U.S. Centers for Disease Control and Prevention, which helped conduct the clinical trial along with the Thailand Ministry of Health.

Sharing needles and drugs is the most common method of HIV transmission in Eastern Europe and Central Asia, where new infections rose 7.7 percent from 2001 to 2011, going against a global downturn in the virus's spread, according to the Joint United Nations Program on HIV/AIDS, or UNAIDS.

Thai researchers along with the C.D.C. ran the study through 17 Bangkok drug-treatment clinics. Addicts are infamously erratic when it comes to keeping appointments, so as an incentive, they were offered $8.75 for each month they stayed in the trial, plus $8.75 for each week they showed up all seven days, plus $1.90 each day they appeared. Those who came in only monthly were paid to keep drug-use diaries.

"We should be under no illusions that these were real-world settings," said Mitchell Warren, executive director for AVAC, an organization that lobbies for AIDS prevention.