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.

In Latin America, transgender women (transwomen or male to female transgenders) have been included in MSM research but without addressing their specific needs in terms of the HIV/AIDS. We present results of the first seroepidemiologic study designed for transwomen in Peru. We conducted a study using respondent driven sampling to recruit transwomen from Lima. Our survey explored sociodemographic characteristics, gender enhancement procedures and sexual behavior. In addition, we conducted laboratory based HIV, genital herpes (HSV2) and syphilis testing. A total of 450 transwomen were recruited between April and July 2009. HIV prevalence was 30%, HSV2: 79% and syphilis: 23%. Sex-work was the main economic activity (64%). Gender enhancement procedures were reported by 70% of the population. Multivariable analysis showed HIV infection to be associated with being older than 35 recent, syphilis infection and HSV2 infection. Transwomen are the group most vulnerable to HIV/AIDS in Peru.

Background Men who have sex with men (MSM) and male-to-female transgender women (TW) are at increased risk of HIV and sexually transmitted infections (STIs). We evaluated factors associated with incidence of HIV, HSV-2, and chlamydia and gonorrhea (anal and pharyngeal). Methods We used data from the Comunidades Positivas trial with MSM/TW who have sex with men in Lima, Peru. Participants were asked about sexual risk behaviors and underwent HIV/STI testing at baseline and 9- and 18-month follow-ups. We used discrete time proportional hazards regression to calculate hazard ratios (HRs) for variables associated with incidence of each STI. Results Among 718 MSM/TW, HIV incidence was 3.6 cases per 100 person-years. HIV incidence was associated with having an incident STI (aHR 3.73). Unprotected receptive anal intercourse was associated with incident anal chlamydia (aHR 2.20). An increased number of sexual partners increased incident HSV-2 (aHR 3.15 for 6–14 partners and 3.97 for 15–46 partners compared to 0–2 partners). Risk of anal gonorrhea decreased with each sexually active year (aHR 0.94) and increased for unprotected compensated sex (aHR 2.36). Risk of pharyngeal gonorrhea also decreased with each year since sexual debut (aHR 0.95). Risk of anal chlamydia decreased with each sexually active year (aHR 0.96), risk increased with reports of unprotected sex work (aHR 1.61), and unprotected receptive anal sex (aHR 2.63). All aHRs have p-values < 0.05. Conclusion MSM/TW experience high incidence of HIV. Up-to-date prevalence and incidence information and identifying factors associated with infection can help develop a more effective combination prevention response.

Introduction: In Peru, transgender women (TW) experience unique vulnerabilities for HIV infection due to factors that limit access to, and quality of, HIV prevention, treatment and care services. Yet, despite recent advances in understanding factors associated with HIV vulnerability among TW globally, limited scholarship has examined how Peruvian TW cope with this reality and how existing community-level resilience strategies are enacted despite pervasive social and economic exclusion facing the community. Addressing this need, our study applies the understanding of social capital as a social determinant of health and examines its relationship to HIV vulnerabilities to TW in Peru. Methods: Using qualitative methodology to provide an in-depth portrait, we assessed (1) intersections between social marginalization, social capital and HIV vulnerabilities; and (2) community-level resilience strategies employed by TW to buffer against social marginalization and to link to needed HIV-related services in Peru. Between January and February 2015, 48 TW participated (mean age = 29, range = 18–44) in this study that included focus group discussions and demographic surveys. Analyses were guided by an immersion crystallization approach and all coding was conducted using Dedoose Version 6.1.18. Results: Themes associated with HIV vulnerability included experiences of multilevel stigma and limited occupational opportunities that placed TW at risk for, and limited their engagement with, existing HIV services. Emergent resiliency-based strategies included peer-to-peer and intergenerational knowledge sharing, supportive clinical services (e.g. group-based clinic attendance) and emotional support through social cohesion (i.e. feeling part of a community). Conclusion: This study highlights the importance of TW communities as support structures that create and deploy social resiliency-based strategies aimed at deterring and mitigating the impact of social vulnerabilities to discrimination, marginalization and HIV risk for individual TW in Peru. Public health strategies seeking to provide HIV prevention, treatment and care for this population will benefit from recognizing existing social capital within TW communities and incorporating its strengths within HIV prevention interventions. At the intersection of HIV vulnerabilities and collective agency, dimensions of bridging and bonding social capital emerged as resiliency strategies used by TW to access needed healthcare services in Peru. Fostering TW solidarity and peer support are key components to ensure acceptability and sustainability of HIV prevention and promotion efforts.

For studies using respondent driven sampling (RDS), the current practice of collecting a sample twice as large as that used in simple random sampling (SRS) (i.e. design effect of 2.00) may not be sufficient. This paper provides empirical evidence of sample-to-sample variability in design effects using data from nine studies in six countries among injecting drug users, female sex workers, men who have sex with men and male-to-female transgender (MTF) persons. We computed the design effect as the variance under RDS divided by the variance under SRS for a broad range of demographic and behavioral variables in each study. We also estimated several measures for each variable in each study that we hypothesized might be related to design effect: the number of waves needed for equilibrium, homophily, and mean network size. Design effects for all studies ranged from 1.20 to 5.90. Mean design effects among all studies ranged from 1.50 to 3.70. A particularly high design effect was found for employment status (design effect of 5.90) of MTF in Peru. This may be explained by a "bottleneck"--defined as the occurrence of a relatively small number of recruitment ties between two groups in the population. A design effect of two for RDS studies may not be sufficient. Since the mean design effect across all studies was 2.33, an effect slightly above 2.00 may be adequate; however, an effect closer to 3.00 or 4.00 might be more appropriate.