Increases in Pre-exposure Prophylaxis Use and Decreases in Condom Use: Behavioral Patterns Among HIV-Negative San Francisco Men Who have Sex with Men, 2004-2017.

Using data from the National HIV Behavioral Surveillance of men who have sex with men (MSM), we estimated the prevalence of sexual behaviors among HIV-negative San Francisco MSM between 2004 and 2017. We estimate a recent increase in the 1-year prevalence of pre-exposure prophylaxis (PrEP) use, from 9.8% in 2014 to 44.9% in 2017. Over that same period, we estimate a decrease in the prevalence of consistent condom use, from 18.5 to 9.4%, and an increase in the percent of individuals with multiple condomless anal intercourse partners. We conclude that while risks for HIV infection may be decreasing among San Francisco MSM due, in part, to increases in PrEP use, the population faces increased risks for other sexually transmitted infections (STIs). Because PrEP alone does not protect against other STIs, we strongly recommend that PrEP users use condoms when possible, routinely screen for STIs, and disclose infections with sexual partners.