(NBC) - Health officials now recommend that people at high risk for HIV take a daily pill to help prevent it.
The new guidelines from the Centers for Disease Control and Prevention were announced Wednesday.
The recommended drug, Truvada, is already used to treat HIV, and has shown to be 90 percent effective in reducing new infections.
Doctors are encouraged to prescribe Truvada for patients who have an HIV positive partner, or who have unprotected sex with people at risk for HIV.
Users should have an HIV test before beginning this treatment, to be sure they're not already infected.
The CDC says about 50,000 people are diagnosed with HIV each year.