Truvada for pre-exposure prophylaxis (PrEP) hasn't seen much widespread adoption, considering that it's the first medication proven to prevent HIV—but that may change now that the U.S. Centers for Disease Control and Prevention (CDC) recommend the drug for certain segments of the population.

The FDA-approved treatment, which involves taking a daily pill, has a reported success rate of 99 percent, has been deemed safe and well tolerated, and is covered by Medicaid and most insurance companies. Many doctors, however, are still unfamiliar with it or are wary of prescribing it. And among men who sleep with men (MSM)—the group with the highest risk of contracting HIV in the United States—there is still some stigma associated with the medication.

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The CDC has joined the chorus of voices recommending the adoption of Truvada by members of several high-risk groups, including non-monogamous MSM who sometimes have unprotected sex, men and women who sometimes have unprotected sex with drug users or MSM, and people who inject illegal drugs.

Infographic: Truvada PrEP for Men Who Sleep with Men »

According to current estimates, fewer than 10,000 (perhaps as few as 3,000) people have currently been prescribed Truvada as an HIV-prevention medication, which costs approximately $13,000 per year. The CDC's new guidelines could raise that number into the hundreds of thousands.

The number of new HIV infections in the U.S. has held steady at 50,000 per year for more than a decade, and a decrease in condom use among MSM is a likely culprit. According to a recent survey by the CDC, the number of gay men who say they've recently had unprotected sex increased by nearly 20 percent between 2005 and 2011. Truvada is intended to be used along with condoms.

Dr. Jonathan Mermin, director of the CDC's National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP), said in a statement that the new guidelines have the potential to save many lives.

“On average, it takes a decade for a scientific breakthrough to be adopted,” he said. “We hope we can shorten that time frame and increase people’s survival.”

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