Current standards could miss some people who should be on Preexposure prophylaxis (PrEP).

Pre-exposure prophylaxis, or PrEP, is a measure that has proven to be highly effective in preventing HIV transmission during unprotected sex. While not entirely foolproof, studies have shown taking daily doses of tenofovir disoproxil-emtricitabine, or Truvada, is 92 percent effective in preventing HIV infection when taken correctly and consistently.

Since 2012, the U.S. Centers for Disease Control and Prevention has recommended PrEP for gay or bisexual men who have had condomless anal sex or been diagnosed with a sexually transmitted infection in the past six months. The CDC also has recommended PrEP for HIV-negative men who have sex with men (MSM) and who are in a relationship with an HIV-positive partner.

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The UCLA study, which was published in the January issue of Sexually Transmitted Diseases, suggests that those guidelines do not go far enough, because they omit important characteristics that could put someone at high risk for becoming infected with the virus that causes AIDS. Working with the Los Angeles LGBT Center, the researchers have developed an online risk assessment calculator, available today, which could fill that gap.

“To the best of our knowledge, this PrEP Calculator is the first of its kind to be based on real-world data,” said Robert Weiss, co-author of the study and a professor of biostatistics at the Fielding School. “We hope that our PrEP calculator will allow more MSM to make a more-informed decision before deciding whether or not PrEP is right for them.”

Click here to read the full press release.