Worldwide, sex workers are disproportionately affected by the HIV pandemic.1 The authors of a review of HIV burden in female sex workers (FSWs) in 50 low-income and middle-income countries reported an overall HIV prevalence of 11·8% (95% CI 11·6–12·0), with a pooled odds of HIV infection of 13·5 (10·0–18·1) compared with the general population of women of reproductive age.2 In many high-income countries and regions, such as Canada, the USA, and Europe, epidemics that initially escalated in people who inject drugs in the mid-1990s shifted to FSWs.3, 4 In settings such as Russia and central and eastern Europe, the scarce data available suggests emerging or established epidemics among FSWs who inject drugs.5, 6 Heterogeneity in HIV prevalence among FSWs varies substantially both across and within regions due to social, political, economic, and cultural factors,7 yet an understanding of how structural factors (eg, contextual factors external to the individual) shape HIV acquisition and transmission risks has only just begun to emerge.
Sex workers—those who exchange sex for money—can be female, male, or transgender. Although most sex workers are female and patronised by male clients (sex buyers), sizeable populations of male and transgender sex workers are present in many settings.8, 9 The work environment and community organisation of sex work varies substantially, including formal sex work establishments (eg, massage parlours, brothels, or other in-call venues), entertainment establishments (eg, bars and nightclubs), informal or out-call venues (eg, hotels, lodges, and saunas), and outdoor settings (eg, streets, parks, and markets). Sex workers might solicit clients independently, both on-street and off-street (eg, self-advertisement online, in newspapers, or by phone or text), or might work for a manager or pimp. In some cases, sex workers might additionally work cooperatively in microbrothels (two or more sex workers working together).
Key messages
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Sex workers face a disproportionately large burden of HIV across concentrated and generalised epidemic settings, with substantial heterogeneity in HIV epidemics and structural determinants, as well as features that are very context specific.
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Fewer than half of epidemiological studies on HIV acquisition and transmission risk among female sex workers explicitly considered structural determinants.
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Epidemiology of HIV and structural determinants among female sex workers is disproportionately drawn from Asia, with large gaps in heavy burden regions of sub-Saharan Africa, Russia, and eastern Europe.
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In Canada and Kenya, where sexual violence has an immediate and sustained effect on non-condom use, elimination of violence by clients, police, and strangers could avert 17–20% of HIV infections among female sex workers and their clients over the next decade.
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Coverage of and access to prevention and treatment among female sex workers lag behind the general population and scale-up to optimal coverage of condoms and HIV care continuum will probably only be feasible alongside other structural change. In heavy HIV-burden settings, such as Mombasa, where antiretroviral therapy and condom access remain suboptimal, scale-up of antiretroviral therapy access to WHO guidelines of a CD4 cell count of less than 500 cells per μL for both FSWs and their clients could avert 34% of HIV infections and even modest scale-up of sex worker-led outreach could avert 20% of HIV infections among FSWs and their clients over the next decade.
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Interventions to promote access to safer sex work environments (eg, changes to venue, management, and policing policies, and access to prevention) could avert a substantial proportion of infections across diverse settings.
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Modelling suggests that across both generalised and concentrated HIV epidemics, decriminalisation of sex work could have the largest effect on the course of the HIV epidemic, averting 33–46% of incident infections over the next decade through combined effects on violence, police harassment, safer work environments, and HIV transmission pathways.
Research and programmes in the past decade suggest that behavioural and biomedical interventions among FSWs alone have had only modest effects on the reduction of HIV at the population-level,2, 10 which has led to calls for combination HIV prevention that includes structural interventions. For example, efforts to roll out antiretroviral therapy (ART) or distribute condoms to FSWs in settings where criminalisation and stigma deter access to condoms or health services continue to hamper HIV prevention, treatment, and care efforts.1, 11, 12 Growing interest has arisen in structural determinants of HIV risk and ecological models that account for these risks among FSWs and other key affected populations (eg, people who inject drugs and men who have sex with men).13, 14, 15 Social epidemiology efforts in sex work have increasingly considered both structure and biology (and behaviour) within a structural determinants framework (figure 1) to better delineate the complex interplay and heterogeneity of HIV acquisition and transmission, and, more aptly, predict epidemic trajectories and intervention targets.13, 16, 17, 18
Despite efforts to consider structural HIV determinants in programmes,16 social science,14, 18 and epidemiological15, 17 literature, the extent to which empirical work characterises the epidemiology of structural factors and HIV among FSWs worldwide, alongside behavioural and biological factors, has yet to be considered. We did a comprehensive search for recent published reports on HIV and FSWs (Jan 1, 2008, to Dec 31, 2013), and assessed the extent to which this literature regarded structural determinants in the mitigation or potentiation of HIV acquisition and transmission risk (panel 1). To further consider key structural factors from our report and available context-specific epidemiological, qualitative, and grey literature, we then modelled potential aversion of HIV infections through structural changes in three cities with high HIV prevalence among FSWs: two low-income and middle-income countries—one concentrated (India) and one generalised (Kenya) epidemic—and one high-income city with overlap with an epidemic of injecting drug use (Canada). These models allowed us to assess heterogeneity of epidemics and key structural determinants, and the potential effect of single and combined interventions (eg, structural changes) in different epidemic contexts.