Social and structural factors are now well accepted as determinants of HIV vulnerabilities. These factors are representative of social, economic, organizational and political inequities. Associated with an improved understanding of multiple levels of HIV risk has been the recognition of the need to implement multi-level HIV prevention strategies. Prevention sciences research and programming aiming to decrease HIV incidence requires epidemiologic studies to collect data on multiple levels of risk to inform combination HIV prevention packages. Proximal individual-level risks, such as sharing injection devices and unprotected penile-vaginal or penile-anal sex, are necessary in mediating HIV acquisition and transmission. However, higher order social and structural-level risks can facilitate or reduce HIV transmission on population levels. Data characterizing these risks is often far more actionable than characterizing individual-level risks. We propose a modified social ecological model (MSEM) to help visualize multi-level domains of HIV infection risks and guide the development of epidemiologic HIV studies. Such a model may inform research in epidemiology and prevention sciences, particularly for key populations including men who have sex with men (MSM), people who inject drugs (PID), and sex workers. The MSEM builds on existing frameworks by examining multi-level risk contexts for HIV infection and situating individual HIV infection risks within wider network, community, and public policy contexts as well as epidemic stage. The utility of the MSEM is demonstrated with case studies of HIV risk among PID and MSM. The MSEM is a flexible model for guiding epidemiologic studies among key populations at risk for HIV in diverse sociocultural contexts. Successful HIV prevention strategies for key populations require effective integration of evidence-based biomedical, behavioral, and structural interventions. While the focus of epidemiologic studies has traditionally been on describing individual-level risk factors, the future necessitates comprehensive epidemiologic data characterizing multiple levels of HIV risk.

Introduction: The West and Central Africa (WCA) sub‐region is the most populous region of sub‐Saharan Africa (SSA), with an estimated population of 356 million living in 24 countries. The HIV epidemic in WCA appears to have distinct dynamics compared to the rest of SSA, being more concentrated among key populations such as female sex workers (FSWs), men who have sex with men (MSM), people who inject drugs (PWID) and clients of FSWs. To explore the epidemiology of HIV in the region, a systematic review of HIV literature among key populations in WCA was conducted since the onset of the HIV epidemic.Methods: We searched the databases PubMed, CINAHL and others for peer‐reviewed articles regarding FSWs, MSM and PWID in 24 countries with no date restriction. Inclusion criteria were sensitive and focused on inclusion of any HIV prevalence data among key populations. HIV prevalence was pooled, and in each country key themes were extracted from the literature.Results: The search generated 885 titles, 214 abstracts and 122 full articles, of which 76 met inclusion and exclusion criteria providing HIV prevalence data. There were 60 articles characterizing the burden of disease among FSWs, eight for their clients, one for both, six for MSM and one for PWID. The pooled HIV prevalence among FSWs was 34.9% (n=14,388/41,270), among their clients was 7.3% (n=435/5986), among MSM was 17.7% (n=656/3714) and among PWID from one study in Nigeria was 3.8% (n=56/1459).Conclusions: The disproportionate burden of HIV among FSWs appears to be consistent from the beginning of the HIV epidemic in WCA. While there are less data for other key populations such as clients of FSWs and MSM, the prevalence of HIV is higher among these men compared to other men in the region. There have been sporadic reports among PWID, but limited research on the burden of HIV among these men and women. These data affirm that the HIV epidemic in WCA appears to be far more concentrated among key populations than the epidemics in Southern and Eastern Africa. Evidence‐based HIV prevention, treatment and care programmes in WCA should focus on engaging populations with the greatest burden of disease in the continuum of HIV care.

Stigma involves discrediting a person or group based on a perceived attribute, behaviour or reputation associated with them. Sex workers (SW) and men who have sex with men (MSM) are key populations who are often at increased risk for the acquisition and transmission of HIV and who are affected by stigma that can negatively impact their health and well-being. Although stigma was included as an indicator in the US National HIV/AIDS Strategic Plan and there have been consultations focused on adding a stigma indicator within PEPFAR and the Global Fund in relation to potentiating HIV risks among key populations, there remains limited consensus on the appropriate measurement of SW- or MSM-associated stigma. Consequently, this systematic review summarizes studies using quantitative, qualitative, or mixed methods approaches to measure stigma affecting sex workers and men who have sex with men. This systematic review included English, French, and Spanish peer-reviewed research of any study design measuring SW- or MSM-associated stigma. Articles were published from January 1, 2004 to March 26, 2014 in PsycINFO, PubMed, EMBASE, CINAHL Plus, Global Health, and World Health Organization Global Health Library Regional Indexes. Of the 541 articles reviewed, the majority measured stigma toward MSM (over 97%), were conducted in North America, used quantitative methods, and focused on internalized stigma. With the inclusion of addressing stigma in several domestic and international HIV strategies, there is a need to ensure the use of validated metrics for stigma. The field to date has completed limited measurement of stigma affecting sex workers, and limited measurement of stigma affecting MSM outside of higher income settings. Moving forward requires a concerted effort integrating validated metrics of stigma into health-related surveys and programs for key populations.

Key populations at high risk for HIV acquisition and transmission, such as MSM, have long been identified as essential subpopulations for epidemiological surveillance of the HIV epidemic. However, surveillance systems in the context of generalized and widespread HIV epidemics have traditionally excluded these men. Emerging and consistent data highlight the disproportionate burden of HIV among MSM that exists when compared with other men of reproductive age across countries with generalized epidemics. Correlates of prevalent HIV infection include individual-level determinants of HIV acquisition and transmission similar to that found in concentrated HIV epidemics and community-level structural factors, such as stigma, being blackmailed, and history of homophobic abuse. HIV incidence was only available from two countries (Kenya, Thailand) with generalized HIV epidemics, but in both settings was an order of magnitude higher than that of other populations. The data presented here suggest that the dynamics of HIV infection among men are more similar across the world than they are different. Many HIV epidemics among average-risk reproductive age adults are slowing across both generalized and concentrated settings. It is in this context that high HIV incidence is observed among MSM, especially young MSM. This trend suggests a change in the trajectory of these HIV epidemics, a change that we may miss if we continue to understudy these populations based on unproved and dated assumptions.

In the USA, gay and other men who have sex with men and transgender women are disproportionately affected by HIV. Uptake of pre-exposure prophylaxis (PrEP), anti-retroviral therapy to prevent HIV-negative individuals from seroconverting if exposed to HIV, by members of this population remains low, particularly among African-Americans. We conducted two focus groups to assess responses to an online social media campaign focusing on PrEP use in New York City. We designed, produced and disseminated the campaign to address knowledge of PrEP; its physical and psychological side effects; and psychosocial barriers related to PrEP adherence and sex shaming. Focus group participants demonstrated a relatively high knowledge of PrEP, although considerable concern remained about side effects, particularly among Black participants. Participants suggested that stigma against PrEP users was declining as PrEP use became more common, but stigma remained, particularly for those not using condoms. Many focus group participants reported distrust of medical providers and were critical of the commodification of HIV prevention by the pharmaceutical industry. Participants reported that those in romantic relationships confronted unique issues regarding PrEP, namely suspicions of infidelity. Finally, Black participants spoke of the need for more tailored and sensitive representations of Black gay men in future programmes and interventions.