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Prevalence of seroadaptive behaviours of men who have sex with men, San Francisco, 2004
  1. J M Snowden1,2,
  2. H F Raymond2,
  3. W McFarland2
  1. 1
    School of Public Health, University of California, Berkeley, California, USA
  2. 2
    San Francisco Department of Public Health, San Francisco, California, USA
  1. Correspondence to Willi McFarland, HIV Epidemiology Section, San Francisco Department of Public Health, 25 Van Ness Avenue, Suite 500, San Francisco, CA 94102-6033, USA; willi_mcfarland{at}


Objectives: To define and measure the prevalence of HIV seroadaptive behaviours among men who have sex with men (MSM).

Methods: A community-based, cross-sectional sample of 1211 HIV negative and 251 HIV positive MSM was recruited in San Francisco in 2004 by time-location sampling. Seroadaptive behaviours were defined by enumerating and characterising all episodes of anal intercourse by partner type, partner HIV serostatus, sexual position and condom use for up to five partners in the preceding 6 months.

Results: Among HIV negative MSM, 37.6% engaged in some form of apparent seroadaptive behaviour, predominantly pure serosorting (24.7%), followed by seropositioning (5.9%), condom serosorting (3.9%) and negotiated safety (3.1%). Among HIV positive men, 43.4% engaged in some form of seroadaptation, including pure serosorting (19.5%), seropositioning (14.3%) and condom serosorting (9.6%). Consistent condom use was reported by 37.1% of HIV negative and 20.7% of HIV positive MSM.

Conclusions: In aggregate, seroadaptive behaviours appear to be the most common HIV prevention strategy adopted by MSM in San Francisco as of 2004. Surveillance and epidemiological studies need to precisely measure seroadaptive behaviours in order to gauge and track the true level of HIV risk in populations. Rigorous prevention research is needed to assess the efficacy of seroadaptive behaviours on individuals’ risk and on the epidemic.

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  • Funding National HIV Behavioural Surveillance is funded by the Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention (U62/CCU923549).

  • Competing interests None.

  • Contributors JMS conducted the main analysis, provided the primary interpretation of results and wrote the first draft of the manuscript. HFR provided primary oversight to the implementation of the study, including data collection and data management, and contributed to the analysis, interpretation and writing of the manuscript. WM provided overall scientific oversight to the study, including the design and conceptualisation of the research question, and made the final manuscript edits.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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