Series www.thelancet.com Published online July 22, 2014 http://dx.doi.org/10.1016/S0140-6736(14)60833-3 1 HIV and sex workers 6 HIV risk and preventive interventions in transgender women sex workers Tonia Poteat, Andrea L Wirtz, Anita Radix, Annick Borquez, Alfonso Silva-Santisteban, Madeline B Deutsch, Sharful Islam Khan, Sam Winter, Don Operario Worldwide, transgender women who engage in sex work have a disproportionate risk for HIV compared with natal male and female sex workers. We reviewed recent epidemiological research on HIV in transgender women and show that transgender women sex workers (TSW) face unique structural, interpersonal, and individual vulnerabilities that contribute to risk for HIV. Only six studies of evidence-based prevention interventions were identified, none of which focused exclusively on TSW. We developed a deterministic model based on findings related to HIV risks and interventions. The model examines HIV prevention approaches in TSW in two settings (Lima, Peru and San Francisco, CA, USA) to identify which interventions would probably achieve the UN goal of 50% reduction in HIV incidence in 10 years. A combination of interventions that achieves small changes in behaviour and low coverage of biomedical interventions was promising in both settings, suggesting that the expansion of prevention services in TSW would be highly effective. However, this expansion needs appropriate sustainable interventions to tackle the upstream drivers of HIV risk and successfully reach this population. Case studies of six countries show context- specific issues that should inform development and implementation of key interventions across heterogeneous settings. We summarise the evidence and knowledge gaps that affect the HIV epidemic in TSW, and propose a research agenda to improve HIV services and policies for this population. Introduction Emerging data show the disproportionate burden of HIV in transgender women and transgender women sex workers (TSW) compared with other populations. 1–3 Worldwide, HIV prevalence is about 19·1% in transgender women, with an odds ratio of 48·8 (95% CI 21·2–76·3) compared with the general adult populations. 1 This prevalence is greater for TSW who have an estimated worldwide HIV prevalence of 27·3%. 2 Laboratory-confirmed HIV data for transgender women is available from only 15 countries (one in North America, six in Asia Pacific, five in Latin America, three in Europe), which emphasises the need for greater attention to the HIV-related requirements of transgender women and TSW. In view of these data, TSW have been identified by UNAIDS as a key population at risk for HIV within the worldwide epidemic response. 4 The term transgender refers to a diverse population whose gender identity or expression differs from their assigned sex at birth. 5 Language about and recognition of this population vary by geography, ethnic origin, and culture, and continue to change over time. Transgender people are culturally recognised with specific social roles in some countries; in others, they receive little public acknowledgment. 6,7 A subset of terms used for this population is presented in the appendix (p 1). TSW have been reported in every continent, often in urban HIV epicentres. However, TSW and their partners and clients, have been largely absent from HIV national surveillance and programme interventions. Invisibility of TSW could be due to misclassification as men who have sex with men (MSM) or natal female sex workers, or attributable to systematic neglect. Sampling, methodo- logical, and theoretical limitations in studies of TSW further undermine an effective public health response to the needs of this population. The proportion of transgender women who sell sex is uncertain, because estimates are limited by non-probability sampling methods and different definitions of sex work. A US-based meta-analysis of HIV in transgender populations estimated that 24–75% Published Online July 22, 2014 http://dx.doi.org/10.1016/ S0140-6736(14)60833-3 This is the sixth in a Series of seven papers about HIV and sex workers For a Lancet HIV and sex workers Series infographic see http://www.thelancet.com/ series/HIV-and-sex-workers/ infographic Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA (T Poteat PhD); Johns Hopkins Medical Institute, Baltimore, MD, USA (A L Wirtz MHS); Callen Lorde Community Health Center, New York, NY, USA (A Radix MD); The HIV Modelling Consortium, Department of Infectious Disease Epidemiology, Imperial College London, London, UK (A Borquez PhD); Unit of Health, Sexuality and Human Development, Universidad Peruana Cayetano Heredia, Lima, Peru (A Silva-Santisteban MD); Center of Excellence for Transgender Health, Department of Family and Community Medicine, University of California—San Francisco, San Francisco, CA, USA (M B Deutsch MD); The Global Fund Project, Center for HIV and AIDS, icddr,b, Dhaka, Bangladesh (S Islam Khan PhD); Division of Policy and Social Studies in Education, Faculty of Education, University of Hong Kong, Hong Kong, China (S Winter PhD); and School of Public Health, Brown University, Department of Behavioral and Social Sciences, Providence, RI, USA (D Operario PhD) Correspondence to: Dr Tonia Poteat, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA tpoteat@jhsph.edu Key messages • Transgender women sex workers (TSW) face disproportionate risk for HIV, but have received little attention in the published literature • TSW have a unique combination of risk factors, including biological (eg, illicit hormone and silicone injection), individual (eg, need for gender affirmation), interpersonal (eg, high-risk male partners), and structural (eg, systemic discrimination and violence based on gender expression, perceived sexuality, and occupation) • HIV research on TSW in Africa, eastern Europe, and central Asia is urgently needed • Evidence-based HIV prevention, care, and treatment interventions for TSW are urgently needed (eg, transgender-affirming HIV educational material, and integration of gender care into HIV care) • Substantial reductions in the number of new infections could be accomplished with small changes in risk factors in this population by combination prevention approaches tailored to the setting