Serosorting among Men at Risk for HIV

This study will obtain cross-sectional and longitudinal data on “HIV serosorting” among MSM in San Francisco. We broadly define HIV serosorting as diverse strategies to reduce HIV acquisition or transmission by intentionally selecting sexual partners of the same serostatus or by modifying sexual practices depending on the partner’s serostatus. We will recruit a community-based cohort of HIV- and HIV+ MSM using a probability-based time-location sampling method with longitudinal follow-up over the Internet.