Did you know that even if you've been exposed to HIV, you might be able to avoid contracting the virus? Starting a course of HIV medications—called post-exposure prophylaxis, or PEP—within 72 hours after exposure might block HIV from taking up residence. (Sooner is better; some doctors advise starting no later than 36 hours.) You must then take the drugs for 28 days.

But many people have never heard of PEP, meaning they won't know to request it—and lower the risk of getting HIV—if they need it. (If, say, they have unprotected sex with someone, then learn that the person is HIV positive.)

So doctors at St. Vincent's Catholic Medical Center in New York City took action. The result: PEP411.com, a website to alert people (especially high-risk young men who have sex with men) that PEP exists. The site teaches the PEP basics and tells you how to get post-exposure prophylaxis in New York if you need it. (To find PEP elsewhere, turn to your doctor or the local ER. If they don't know about PEP, they can contact the CDC.)

PEP has been available for some time to hospital workers who experience accidents such as a needle stick or other exposure to HIV-positive blood. But for people exposed to the virus during non-occupational activities, such as sex without condoms or IV-drug use with shared equipment, it has been harder to get.

Armed with the information provided by PEP411, people may be better able to take advantage of PEP. While it's not foolproof, PEP does reduce the risk of becoming HIV positive after an exposure to the virus.