The U.S. government has recommended that hundreds of thousands of people at risk for AIDS take a daily drug that is effective in preventing the virus.

The Centers for Disease Control and Prevention issued an official recommendation Wednesday that people at high risk of contracting AIDS take a combination of two medicines called Pre-exposure prophylaxis (PrEP), which is known to help prevent infection of HIV, the virus that causes the deadly, incurable disease.

If taken regularly, the drug can reduce risk of infection in high-risk populations by up to 92%, the CDC says.

PreP comes in a generic version called Truvada and is used widely in AIDS treatment programs in poor countries. The CDC’s recommendation could, if followed widely, increase the number of people taking the drug in the U.S. from fewer than 10,000 to half a million, the New York Times reported.

The CDC recommends the drug, in combination with condom use, to gay men who have sex without using condoms, heterosexuals who sleep with intravenous drug users or bisexuals, and anyone who has sex with someone they know to be HIV-positive, as well as anyone who shares needles or injects drugs.

HIV rates have held stubbornly flat for the past decade, and a sharp decline in condom usage has raised concerns among health officials.

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