Estimated Population Size of Men Who Have Sex with Men, San Francisco, 2017.

Current population size estimates of communities at risk for HIV are needed to adequately plan interventions and care. We update the estimated number of men who have sex with men (MSM) living in San Francisco. Multiple data sources and approaches, including population growth, registered HIV cases, wisdom of the crowd, and a published estimate on the proportion of adults who are MSM were used for estimation. The several estimates were synthesized into a final figure with acceptable bounds using a Bayesian method. We project 69,974 (acceptable bounds 65,523-74,323) MSM are living in San Francisco as of the beginning of 2017. The population of MSM in San Francisco has increased by 19.4% since 2014.