Data and methods to characterize the role of sex work and to inform sex work programs in generalized HIV epidemics: evidence to challenge assumptions

Challenges and Opportunities in Big Data Science to Address Health Inequities and Focus the HIV Response

PURPOSE OF REVIEW

Big Data Science can be used to pragmatically guide the allocation of resources within the context of national HIV programs and inform priorities for intervention. In this review, we discuss the importance of grounding Big Data Science in the principles of equity and social justice to optimize the efficiency and effectiveness of the global HIV response.

RECENT FINDINGS

Social, ethical, and legal considerations of Big Data Science have been identified in the context of HIV research. However, efforts to mitigate these challenges have been limited. Consequences include disciplinary silos within the field of HIV, a lack of meaningful engagement and ownership with and by communities, and potential misinterpretation or misappropriation of analyses that could further exacerbate health inequities. Big Data Science can support the HIV response by helping to identify gaps in previously undiscovered or understudied pathways to HIV acquisition and onward transmission, including the consequences for health outcomes and associated comorbidities. However, in the absence of a guiding framework for equity, alongside meaningful collaboration with communities through balanced partnerships, a reliance on big data could continue to reinforce inequities within and across marginalized populations.

Comparison of Empirically Derived and Model-Based Estimates of Key Population HIV Incidence and the Distribution of New Infections by Population Group in Sub-Saharan Africa

BACKGROUND

The distribution of new HIV infections among key populations, including female sex workers (FSWs), gay men and other men who have sex with men (MSM), and people who inject drugs (PWID) are essential information to guide an HIV response, but data are limited in sub-Saharan Africa (SSA). We analyzed empirically derived and mathematical model-based estimates of HIV incidence among key populations and compared with the Joint United Nations Programme on HIV/AIDS (UNAIDS) estimates.

METHODS

We estimated HIV incidence among FSW and MSM in SSA by combining meta-analyses of empirical key population HIV incidence relative to the total population incidence with key population size estimates (KPSE) and HIV prevalence. Dynamic HIV transmission model estimates of HIV incidence and percentage of new infections among key populations were extracted from 94 country applications of 9 mathematical models. We compared these with UNAIDS-reported distribution of new infections, implied key population HIV incidence and incidence-to-prevalence ratios.

RESULTS

Across SSA, empirical FSW HIV incidence was 8.6-fold (95% confidence interval: 5.7 to 12.9) higher than total population female 15-39 year incidence, and MSM HIV incidence was 41.8-fold (95% confidence interval: 21.9 to 79.6) male 15-29 year incidence. Combined with KPSE, these implied 12% of new HIV infections in 2021 were among FSW and MSM (5% and 7% respectively). In sensitivity analysis varying KPSE proportions within 95% uncertainty range, the proportion of new infections among FSW and MSM was between 9% and 19%. Insufficient data were available to estimate PWID incidence rate ratios. Across 94 models, median proportion of new infections among FSW, MSM, and PWID was 6.4% (interquartile range 3.2%-11.7%), both much lower than the 25% reported by UNAIDS.

CONCLUSION

Empirically derived and model-based estimates of HIV incidence confirm dramatically higher HIV risk among key populations in SSA. Estimated proportions of new infections among key populations in 2021 were sensitive to population size assumptions and were substantially lower than estimates reported by UNAIDS.

Acceptability of the dapivirine vaginal ring for HIV-1 prevention among women reporting engagement in transactional sex

We assessed if acceptability of the dapivirine vaginal ring for HIV prevention differed among the subgroup of women who reported engaging in transactional sex prior to enrollment in MTN-020/ASPIRE (phase III trial in Malawi, South Africa, Uganda, and Zimbabwe, 2012-2015; n = 2629). Transactional sex was defined as receipt of money, goods, gifts, drugs, or shelter in exchange for sex in the past year. Dimensions of acceptability included: ease of use and physical sensation in situ, impacts on sex, partner's opinion, and likelihood of future use. We used Poisson regression models with robust standard errors to compare risk of acceptability challenges by baseline history of transactional sex. At product discontinuation, women exchanging sex found the ring comfortable (90%), easy to insert (92%) and nearly all (96%) were likely to use the ring in the future. Women who had exchanged sex were more likely to report feeling the ring during sex (ARR 1.43, 95% CI: 1.09, 1.89; p = 0.01) and slightly more likely to mind wearing the ring during menses (ARR 1.22, 95% CI: 1.01, 1,46; p = 0.04) and during sex (ARR 1.22, 95% CI: 1.02, 1.45; p = 0.03). Messaging and counseling should include enhanced support for use during sex and menses to support optimal use.

Mobility and HIV vulnerabilities among female sex workers in Guinea-Bissau: findings from an integrated bio-behavioral survey

BACKGROUND

Mobility is an important risk determinant for HIV given the potential for intermittent access to HIV services. Mobility may be particularly relevant among female sex workers, (FSW) who have been shown to be at high risk for HIV in settings around the world. Data regarding the role mobility plays in exacerbating HIV risks among FSW across Sub-Saharan Africa remains limited, and data on FSW in Guinea-Bissau is sparse.

METHODS

FSW in four regions of Guinea-Bissau were recruited with a respondent-driven sampling (RDS) method and participated in an integrated bio-behavioral survey between September 27, 2017 and January 26, 2018. Associations between reported general mobility, mobility to or residence in Bissau, and social and HIV vulnerabilities among FSW in Guinea-Bissau were assessed using multivariable logistic regression models. Population proportions were weighted for RDS sampling, while logistic regression models were not.

RESULTS

Survey respondents included 323 individuals in Bissau, 45 in Bissorã, 140 in Bafatá, and 59 in Gabu. Statistical analyses demonstrated that mobility to more than one destination was significantly associated with recent sex without a condom (ie, sex without a condom within the last three sex acts) with both clients (aOR: 2.47 (95% CI: 1.08, 5.64)) and non-paying partners (aOR: 5.39 (95% CI: 2.61, 11.15)) compared to non-mobility. However, mobility to one or more locations was also associated with higher odds of receiving HIV prevention information, and mobility to more than one location was associated with participating in programming with HIV-related organizations.

CONCLUSIONS

These results suggest that while some prevention services including HIV prevention information reach mobile FSW in Guinea-Bissau more than their non-mobile counterparts, the higher rates of condomless sex among mobile FSW suggest that HIV prevention needs may remain unmet for mobile FSW in Guinea-Bissau. Additionally, the results suggest a nuanced relationship between mobility, place of residence, and HIV and social vulnerabilities and prevention indicators.

"I decided in my heart I have to complete the sessions": A qualitative study on the acceptability of an evidence-based HIV risk reduction intervention among women engaged in sex work in Uganda

BACKGROUND

The HIV burden remains a critical public health concern and women engaged in sex work [WESW] are at significantly higher risk compared to the general adult population. Similar to other sub-Saharan African countries, Uganda reports high rates of HIV prevalence among WESW. Yet, they have not been targeted by theory-informed HIV prevention intervention approaches.

METHODS

We conducted semi-structured in-depth interviews with 20 WESW upon intervention completion to explore their experiences with an evidence-based HIV risk reduction intervention that was implemented as part of a combination intervention tested in a clinical trial in Uganda (2018-2023. Specifically, we explored their initial motivations and concerns for participating in the intervention, barriers and facilitators to attendance, and their feedback on specific intervention characteristics.

RESULTS

The main expectations revolved around access to health-related information, including information on STIs, HIV, and PrEP as well as on how one can protect themselves while engaging in sex work. Initial concerns were around potential breach of confidentiality and fear of arrest. The main facilitators for session attendance were the motivation to learn health-related information, the attitude of facilitators, and the incentives received for participation, whereas main challenges were related to family commitments and work schedules. WESW appreciated the group format of the intervention and found the location and times of the intervention delivery acceptable.

DISCUSSION AND CONCLUSIONS

Overall, our findings suggest that the HIV risk reduction intervention was appropriate and acceptable to WESW. Yet, WESW experience unique concerns and barriers that need to be accounted for when designing interventions targeting this population, especially in resource-limited settings where sex work is illegal and highly stigmatized.

CLINICAL TRIAL REGISTRATION

NCT03583541.

Global population attributable fraction of potentially modifiable risk factors for mental disorders: a meta-umbrella systematic review

Numerous risk factors for mental disorders have been identified. However, we do not know how many disorders we could prevent and to what extent by modifying these risk factors. This study quantifies the Population Attributable Fraction (PAF) of potentially modifiable risk factors for mental disorders. We conducted a PRISMA 2020-compliant (Protocol: https://osf.io/hk2ag ) meta-umbrella systematic review (Web of Science/PubMed/Cochrane Central Register of Reviews/Ovid/PsycINFO, until 05/12/2021) of umbrella reviews reporting associations between potentially modifiable risk factors and ICD/DSM mental disorders, restricted to highly convincing (class I) and convincing (class II) evidence from prospective cohorts. The primary outcome was the global meta-analytical PAF, complemented by sensitivity analyses across different settings, the meta-analytical Generalised Impact Fraction (GIF), and study quality assessment (AMSTAR). Seven umbrella reviews (including 295 meta-analyses and 547 associations) identified 28 class I-II risk associations (23 risk factors; AMSTAR: 45.0% high-, 35.0% medium-, 20.0% low quality). The largest global PAFs not confounded by indication were 37.84% (95% CI = 26.77-48.40%) for childhood adversities and schizophrenia spectrum disorders, 24.76% (95% CI = 13.98-36.49%) for tobacco smoking and opioid use disorders, 17.88% (95% CI = not available) for job strain and depression, 14.60% (95% CI = 9.46-20.52%) for insufficient physical activity and Alzheimer's disease, 13.40% (95% CI = 7.75-20.15%) for childhood sexual abuse and depressive disorders, 12.37% (95% CI = 5.37-25.34%) for clinical high-risk state for psychosis and any non-organic psychotic disorders, 10.00% (95% CI = 5.62-15.95%) for three metabolic factors and depression, 9.73% (95% CI = 4.50-17.30%) for cannabis use and schizophrenia spectrum disorders, and 9.30% (95% CI = 7.36-11.38%) for maternal pre-pregnancy obesity and ADHD. The GIFs confirmed the preventive capacity for these factors. Addressing several potentially modifiable risk factors, particularly childhood adversities, can reduce the global population-level incidence of mental disorders.

Risk heterogeneity in compartmental HIV transmission models of ART as prevention in Sub-Saharan Africa: A scoping review

BACKGROUND

Transmission models provide complementary evidence to clinical trials about the potential population-level incidence reduction attributable to ART (ART prevention impact). Different modelling assumptions about risk heterogeneity may influence projected ART prevention impacts. We sought to review representations of risk heterogeneity in compartmental HIV transmission models applied to project ART prevention impacts in Sub-Saharan Africa.

METHODS

We systematically reviewed studies published before January 2020 that used non-linear compartmental models of sexual HIV transmission to simulate ART prevention impacts in Sub-Saharan Africa. We summarized data on model structure/assumptions (factors) related to risk and intervention heterogeneity, and explored multivariate ecological associations of ART prevention impacts with modelled factors.

RESULTS

Of 1384 search hits, 94 studies were included. 64 studies considered sexual activity stratification and 39 modelled at least one key population. 21 studies modelled faster/slower ART cascade transitions (HIV diagnosis, ART initiation, or cessation) by risk group, including 8 with faster and 4 with slower cascade transitions among key populations versus the wider population. In ecological analysis of 125 scenarios from 40 studies (subset without combination intervention), scenarios with risk heterogeneity that included turnover of higher risk groups were associated with smaller ART prevention benefits. Modelled differences in ART cascade across risk groups also influenced the projected ART benefits, including: ART prioritized to key populations was associated with larger ART prevention benefits. Of note, zero of these 125 scenarios considered lower ART coverage among key populations.

CONCLUSION

Among compartmental transmission models applied to project ART prevention impacts in Sub-Saharan Africa, representations of risk heterogeneity and projected impacts varied considerably. Inclusion/exclusion of risk heterogeneity with turnover, and intervention heterogeneity across risk groups could influence the projected impacts of ART scale-up. These findings highlight a need to capture risk heterogeneity with turnover and cascade heterogeneity when projecting ART prevention impacts.

Adequate funding of comprehensive community-based programs for key populations needed now more than ever to reach and sustain HIV targets

Introduction

Globally, over half of the estimated new HIV infections now occur among key populations, including men who have sex with men, sex workers, people who inject drugs, transgender individuals, and people in prisons and other closed settings, and their sexual partners. Reaching epidemic control will, for many countries, increasingly require intensified programming and targeted resource allocation to meet the needs of key populations and their sexual partners. However, insufficient funding, both in terms of overall amounts and the way the funding is spent, contributes to the systematic marginalization of key populations from needed HIV services.

Discussion

The Joint United Nations Programme on HIV/AIDS (UNAIDS) has recently highlighted the urgent need to take action to end inequalities, including those faced by key populations, which have only been exacerbated by the COVID‐19 pandemic. To address these inequalities and improve health outcomes, key population programs must expand the use of a trusted access platform, scale up differentiated service delivery models tailored to the needs of key populations, rollout structural interventions and ensure service integration. These critical program elements are often considered “extras,” not necessities, and consequently costing studies of key population programs systematically underestimate the total and unitary costs of services for key populations. Findings from a recent costing study from the LINKAGES project suggest that adequate funding for these four program elements can yield benefits in program performance. Despite this and other evidence, the lack of data on the true costs of these elements and the costs of failing to provide them prevents sufficient investment in these critical elements.

Conclusions

As nations strive to reach the 2030 UNAIDS goals, donors, governments and implementers should reconsider the true, but often hidden costs in future healthcare dollars and in lives if they fail to invest in the community‐based and community‐driven key population programs that address structural inequities. Supporting these efforts contributes to closing the remaining gaps in the 95‐95‐95 goals. The financial and opportunity cost of perpetuating inequities and missing those who must be reached in the last mile of HIV epidemic control must be considered.

Automating document classification with distant supervision to increase the efficiency of systematic reviews: A case study on identifying studies with HIV impacts on female sex workers

There remains a limited understanding of the HIV prevention and treatment needs among female sex workers in many parts of the world. Systematic reviews of existing literature can help fill this gap; however, well-done systematic reviews are time-demanding and labor-intensive. Here, we propose an automatic document classification approach to a systematic review to significantly reduce the effort in reviewing documents and optimizing empiric decision making. We first describe a manual document classification procedure that is used to curate a pertinent training dataset and then propose three classifiers: a keyword-guided method, a cluster analysis-based method, and a random forest approach that utilizes a large set of feature tokens. This approach is used to identify documents studying female sex workers that contain content relevant to either HIV or experienced violence. We compare the performance of the three classifiers by cross-validation in terms of area under the curve of the receiver operating characteristic and precision and recall plot, and found random forest approach reduces the amount of manual reading for our example by 80%; in sensitivity analysis, we found that even trained with only 10% of data, the classifier can still avoid reading 75% of future documents (68% of total) while retaining 80% of relevant documents. In sum, the automated procedure of document classification presented here could improve both the precision and efficiency of systematic reviews and facilitate live reviews, where reviews are updated regularly. We expect to obtain a reasonable classifier by taking 20% of retrieved documents as training samples. The proposed classifier could also be used for more meaningfully assembling literature in other research areas and for rapid documents screening with a tight schedule, such as COVID-related work during the crisis.

Evaluating the quality of HIV epidemiologic evidence for populations in the absence of a reliable sampling frame: a modified quality assessment tool

BACKGROUND

Sampling frames rarely exist for key populations at highest risk for HIV, such as sex workers, men who have sex with men, people who use drugs, and transgender populations. Without reliable sampling frames, most data collection relies on non-probability sampling approaches including network-based methods (e.g. respondent driven sampling) and venue-based methods (e.g. time-location sampling). Quality of implementation and reporting of these studies is highly variable, making wide-ranging estimates often difficult to compare. Here, a modified quality assessment tool, Global.HIV Quality Assessment Tool for Data Generated through Non-Probability Sampling (GHQAT), was developed to evaluate the quality of HIV epidemiologic evidence generated using non-probability methods.

METHODS

The GHQAT assesses three main domains: study design, study implementation, and indicator-specific criteria(prevalence, incidence, HIV continuum of care, and population size estimates). The study design domain focuses primarily on the specification of the target and study populations. The study implementation domain is concerned with sampling implementation. Each indicator-specific section contains items relevant to that specific indicator. A random subset of 50 studies from a larger systematic review on epidemiologic data related to HIV and key populations was generated and reviewed using the GHQAT by two independent reviewers. Inter-rater reliability was assessed by calculating intraclass correlation coefficients for the scores assigned to study design, study implementation and each of the indicator-specific criteria. Agreement was categorized as poor(0.00-0.50), fair(0.51-0.70), and good(0.71-1.00). The distribution of good, fair, and poor scores for each section was described.

RESULTS

Overall, agreement between the two independent reviewers was good(ICC >0.7). Agreement was best for the section evaluating the HIV continuum of care(ICC = 0.96). For HIV incidence, perfect agreement was observed, but this is likely due to the small number of studies reviewed that assessed incidence(n = 3). Of the studies reviewed, 2% (n = 1) received a score of "poor" for study design, while 50% (n = 25) received a score of "poor" for study implementation.

CONCLUSIONS

Addressing HIV prevention and treatment needs of key populations is increasingly understood to be central to HIV responses across HIV epidemic settings, though data characterizing specific needs remains highly variable with the least amount of information in the most stigmatizing settings. Here, we present an efficient tool to guide HIV prevention and treatment programs as well as epidemiological data collection by reliably synthesizing the quality of available non-probability based epidemiologic information for key populations. This tool may help shed light on how researchers may improve not only the implementation of, but also the reporting on their studies.

Overlapping Key Populations and HIV Transmission in Tijuana, Mexico: A Modelling Analysis of Epidemic Drivers

Tijuana, Mexico, has a concentrated HIV epidemic among overlapping key populations (KPs) including people who inject drugs (PWID), female sex workers (FSW), their male clients, and men who have sex with men (MSM). We developed a dynamic HIV transmission model among these KPs to determine the extent to which their unmet prevention and treatment needs is driving HIV transmission. Over 2020-2029 we estimated the proportion of new infections acquired in each KP, and the proportion due to their unprotected risk behaviours. We estimate that 43.7% and 55.3% of new infections are among MSM and PWID, respectively, with FSW and their clients making-up < 10% of new infections. Projections suggest 93.8% of new infections over 2020-2029 will be due to unprotected sex between MSM or unsafe injecting drug use. Prioritizing interventions addressing sexual and injecting risks among MSM and PWID are critical to controlling HIV in Tijuana.

Reproductive Health Concerns of Women With High Risk Sexual Behaviors

Introduction

Expansion of reproductive health services and addressing its different aspects in national and international levels is an important step towards ensuring family and public health. Female sex workers are a vulnerable population that are exposed to high risk sexual behaviors and increased incidence of co-morbid health problems. This study aims to identify the concerns of women with high risk sexual behaviors. Clarifying different aspects of reproductive health and its problems in female sex workers can assist relevant authorities to plan and intervene on reproductive health and to provide more effective solutions on this issue.

Methods

A qualitative study was conducted using a conventional content analysis approach. Snowball sampling was performed in 20 volunteer women with high risk sexual behaviors through in-depth semi-structured interviews conducted in drop-in centers, triangle centers, etc. The data were analyzed through conventional content analysis using the MAXQDA software.

Results

Five main categories and 13 subcategories emerged during the interviews. The main categories included violence, fear, and lack of knowledge, stigma, and psychological problems. Women with high risk sexual behaviors have several reproductive health concerns, including unwanted pregnancy, abortion, STIs (Sexually transmitted infections), HIV, etc. In addition, different types of violence and threats against women, intimidation, objectification, stigma, unresponsiveness of counselling centers, patriarchal culture, gender inequality, etc. were observed in these women.

Conclusion

The study revealed that women in this study experienced deep problems of reproductive health and little attention is paid to them by authorities. Proper planning and appropriate solutions should be provided to solve the problems of these women and the society.

Estimating the epidemic consequences of HIV prevention gaps among key populations

INTRODUCTION

HIV epidemic appraisals are used to characterize heterogeneity and inequities in the context of the HIV pandemic and the response. However, classic measures used in appraisals have been shown to underestimate disproportionate risks of onward transmission, particularly among key populations. In response, a growing number of modelling studies have quantified the consequences of unmet prevention and treatment needs (prevention gaps) among key populations as a transmission population attributable fraction over time (tPAFt ). To aid its interpretation and use by programme implementers and policy makers, we outline and discuss a conceptual framework for understanding and estimating the tPAFt via transmission modelling as a measure of onward transmission risk from HIV prevention gaps; and discuss properties of the tPAFt .

DISCUSSION

The distribution of onward transmission risks may be defined by who is at disproportionate risk of onward transmission, and under which conditions. The latter reflects prevention gaps, including secondary prevention via treatment: the epidemic consequences of which may be quantified by the tPAFt . Steps to estimating the tPAFt include parameterizing the acquisition and onward transmission risks experienced by the subgroup of interest, defining the most relevant counterfactual scenario, and articulating the time-horizon of analyses and population among whom to estimate the relative difference in cumulative transmissions; such steps could reflect programme-relevant questions about onward transmission risks. Key properties of the tPAFt include larger onward transmission risks over longer time-horizons; seemingly mutually exclusive tPAFt measures summing to greater than 100%; an opportunity to quantify the magnitude of disproportionate onward transmission risks with a per-capita tPAFt ; and that estimates are conditional on what has been achieved so far in reducing prevention gaps and maintaining those conditions moving forward as the status quo.

CONCLUSIONS

The next generation of HIV epidemic appraisals has the potential to support a more specific HIV response by characterizing heterogeneity in disproportionate risks of onward transmission which are defined and conditioned on the past, current and future prevention gaps across subsets of the population.

Overview of the epidemiological conditions of HIV among key populations in Africa

INTRODUCTION

Despite extraordinary progress in HIV treatment coverage and expanding access to HIV prevention services and that multiple African countries are on track in their efforts to reach 90-90-90 goals, the epidemic continues to persist, with prevalence and incidence rates too high in some parts of the continent to achieve epidemic control. While data sources are improving, and research studies on key populations in specific contexts have improved, work on understanding the HIV burdens and barriers to services for these populations remains sparse, uneven and absent altogether in multiple settings. More data have become available in the last several years, and data published in 2010 or more recently are reviewed here for each key population. This scoping review assesses the current epidemiology of HIV among key populations in Africa and the social and political environments that contribute to the epidemic, both of which suggest that without significant policy reform, these epidemics will likely continue.

RESULTS AND DISCUSSION

Across Africa, the HIV epidemic is most severe among key populations including women and men who sell or trade sex, men who have sex with men, people who inject drugs, transgender women who have sex with men and prisoners and detainees. These groups account for the majority of new infections in West and Central Africa, and an estimated 25% of new infections in East and Southern Africa, despite representing relatively small proportions of those populations. The HIV literature in Africa emphasizes that despite significant health needs, key populations experience barriers to accessing services within the healthcare and legal justice systems. Current shortcomings of surveillance systems in enumerating key populations impact the way funding mechanisms and resources are allocated and distributed. Adapting more equitable and epidemiologically sound frameworks will be necessary for current and future HIV programming investments.

CONCLUSIONS

Through this review, the available literature on HIV epidemiology among key populations in Africa brings to light a number of surveillance, programmatic and research gaps. For many communities, interventions targeting the health and security conditions continue to be minimal. Compelling evidence suggests that sweeping policy and programmatic changes are needed to effectively tackle the persistent HIV epidemic in Africa.

High HIV Prevalence and Low HIV-Service Engagement Among Young Women Who Sell Sex: A Pooled Analysis Across 9 Sub-Saharan African Countries

BACKGROUND

Epidemiological data are needed to characterize the age-specific HIV burden and engagement in HIV services among young, marginalized women in sub-Saharan Africa.

SETTING

Women aged ≥18 years who reported selling sex were recruited across 9 countries in Southern, Central, and West Africa through respondent driven sampling (N = 6592).

METHODS

Individual-level data were pooled and age-specific HIV prevalence and antiretroviral therapy (ART) coverage were estimated for each region using generalized linear mixed models. HIV-service engagement outcomes (prior HIV testing, HIV status awareness, and ART use) were compared among women living with HIV across age strata (18-19, 20-24, and ≥25 years) using generalized estimating equations.

RESULTS

By age 18%-19%, 45.4% [95% confidence interval (CI): 37.9 to 53.0], 5.8% (95% CI: 4.3 to 7.8), and 4.0% (95% CI: 2.9 to 5.4) of young women who sell sex were living with HIV in Southern, Central, and West Africa respectively. Prevalence sharply increased during early adulthood in all regions, but ART coverage was suboptimal across age groups. Compared with adult women ≥25, young women aged 18-19 were less likely to have previously tested for HIV [prevalence ratio (PR) 0.76; 95% CI: 0.72 to 0.80], less likely to already be aware of their HIV status (PR 0.48; 95% CI: 0.35 to 0.64), and less likely to be taking ART (PR 0.67; 95% CI: 0.59 to 0.75).

CONCLUSIONS

HIV prevalence was already high by age 18-19 in this pooled analysis, demonstrating the need for prevention efforts that reach women who sell sex early in their adolescence. ART coverage remained low, with women in the youngest age group the least engaged in HIV-related services. Addressing barriers to HIV service delivery among young women who sell sex is central to a comprehensive HIV response.

Estimating the Population Size of Female Sex Workers in Zimbabwe: Comparison of Estimates Obtained Using Different Methods in Twenty Sites and Development of a National-Level Estimate

National-level population size estimates (PSEs) for hidden populations are required for HIV programming and modelling. Various estimation methods are available at the site-level, but it remains unclear which are optimal and how best to obtain national-level estimates.

Using factor analyses to estimate the number of female sex workers across Malawi from multiple regional sources

PURPOSE

Human immunodeficiency virus (HIV) risks are heterogeneous in nature even in generalized epidemics. However, data are often missing for those at highest risk of HIV, including female sex workers. Statistical models may be used to address data gaps where direct, empiric estimates do not exist.

METHODS

We proposed a new size estimation method that combines multiple data sources (the Malawi Biological and Behavioral Surveillance Survey, the Priorities for Local AIDS Control Efforts study, and the Malawi Demographic Household Survey). We used factor analysis to extract information from auxiliary variables and constructed a linear mixed effects model for predicting population size for all districts of Malawi.

RESULTS

On average, the predicted proportion of female sex workers among women of reproductive age across all districts was about 0.58%. The estimated proportions seemed reasonable in comparing with a recent study Priorities for Local AIDS Control Efforts II (PLACE II). Compared with using a single data source, we observed increased precision and better geographic coverage.

CONCLUSIONS

We illustrate how size estimates from different data sources may be combined for prediction. Applying this approach to other subpopulations in Malawi and to countries where size estimate data are lacking can ultimately inform national modeling processes and estimate the distribution of risks and priorities for HIV prevention and treatment programs.

Contribution of high risk groups' unmet needs may be underestimated in epidemic models without risk turnover: A mechanistic modelling analysis

Background

Epidemic models of sexually transmitted infections (STIs) are often used to characterize the contribution of risk groups to overall transmission by projecting the transmission population attributable fraction (tPAF) of unmet prevention and treatment needs within risk groups. However, evidence suggests that STI risk is dynamic over an individual’s sexual life course, which manifests as turnover between risk groups. We sought to examine the mechanisms by which turnover influences modelled projections of the tPAF of high risk groups.

Methods

We developed a unifying, data-guided framework to simulate risk group turnover in deterministic, compartmental transmission models. We applied the framework to an illustrative model of an STI and examined the mechanisms by which risk group turnover influenced equilibrium prevalence across risk groups. We then fit a model with and without turnover to the same risk-stratified STI prevalence targets and compared the inferred level of risk heterogeneity and tPAF of the highest risk group projected by the two models.

Results

The influence of turnover on group-specific prevalence was mediated by three main phenomena: movement of previously high risk individuals with the infection into lower risk groups; changes to herd effect in the highest risk group; and changes in the number of partnerships where transmission can occur. Faster turnover led to a smaller ratio of STI prevalence between the highest and lowest risk groups. Compared to the fitted model without turnover, the fitted model with turnover inferred greater risk heterogeneity and consistently projected a larger tPAF of the highest risk group over time.

Implications

If turnover is not captured in epidemic models, the projected contribution of high risk groups, and thus, the potential impact of prioritizing interventions to address their needs, could be underestimated. To aid the next generation of tPAF models, data collection efforts to parameterize risk group turnover should be prioritized.

•

A new framework for parameterizing turnover in risk groups is developed.

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Mechanisms by which turnover influences sexually transmitted infection (STI), prevalence in risk groups are examined.

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Turnover reduces the ratio of equilibrium STI prevalence in high vs low risk groups.

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Inferred risk heterogeneity is higher when fitting transmission models with turnover.

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Ignoring turnover in risk could underestimate the transmission population attributable fraction (tPAF), of high risk groups to the overall epidemic.

Evolving HIV epidemics: the urgent need to refocus on populations with risk

Purpose of review

To explore the comparative importance of HIV infections among key populations and their intimate partners as HIV epidemics evolve, and to review implications for guiding responses.

Recent findings

Even as concentrated epidemics evolve, new infections among current and former key population members and their intimate partners dominate new infections. Prevalent infections in the general population grow primarily because of key population turnover and infections among their intimate partners. In generalized epidemic settings, data and analysis on key populations are often inadequate to assess the impact of key population-focused responses, so they remain limited in coverage and under resourced. Models must incorporate downstream infections in comparing impacts of alternative responses.

Summary

Recognize that every epidemic is unique, moving beyond the overly simplistic concentrated/generalized epidemic paradigm that can misdirect resources. Guide HIV responses by gathering and using locally relevant data, understanding risk heterogeneity, and applying modeling at both national and sub-national levels to optimize resource allocations among different populations for greatest impact. Translate this improved understanding into clear, unequivocal advice for policymakers on where to focus for impact, breaking them free of the generalized/concentrated paradigm limiting their thinking and affecting their decisions.

Characterizing Multi-level Determinants of HIV Prevalence Among Female Sex Workers in Maseru and Maputsoe, Lesotho

Lesotho has a broadly generalized HIV epidemic with nearly one in three reproductive-aged women living with HIV. Given this context, there has been limited research on specific HIV risks. In response, this study aimed to characterize the burden of HIV and multi-level correlates of HIV infection amongst female sex workers (FSW) in Lesotho. Respondent driven sampling was used to recruit 744 FSW from February to September 2014 in Maseru and Maputsoe, Lesotho. Robust Poisson regression was used to model weighted prevalence ratios (PR) for HIV, leveraging a modified social ecological model. The HIV prevalence among participants was 71.9% (534/743), with a mean age of 26.8 (SD 7.2). Both individual and structural determinants involving stigma were significantly associated with HIV. Women with the highest enacted stigma score (≥ 5) had a 26% higher prevalence of HIV than individuals that did not experience any stigma (PR 1.26, 95% CI 1.01, 1.57). These data reinforce the extraordinarily high burden of HIV borne by FSW even in the context of the generalized HIV epidemic observed in Lesotho and across southern Africa. Moreover, stigma represents a structural determinant that is fundamental to an effective HIV response for FSW in Lesotho.

The role of sex work laws and stigmas in increasing HIV risks among sex workers

Globally HIV incidence is slowing, however HIV epidemics among sex workers are stable or increasing in many settings. While laws governing sex work are considered structural determinants of HIV, individual-level data assessing this relationship are limited. In this study, individual-level data are used to assess the relationships of sex work laws and stigmas in increasing HIV risk among female sex workers, and examine the mechanisms by which stigma affects HIV across diverse legal contexts in countries across sub-Saharan Africa. Interviewer-administered socio-behavioral questionnaires and biological testing were conducted with 7259 female sex workers between 2011-2018 across 10 sub-Saharan African countries. These data suggest that increasingly punitive and non-protective laws are associated with prevalent HIV infection and that stigmas and sex work laws may synergistically increase HIV risks. Taken together, these data highlight the fundamental role of evidence-based and human-rights affirming policies towards sex work as part of an effective HIV response.

Vulnerabilities at First Sex and Their Association With Lifetime Gender-Based Violence and HIV Prevalence Among Adolescent Girls and Young Women Engaged in Sex Work, Transactional Sex, and Casual Sex in Kenya

BACKGROUND

Adolescent girls and young women (AGYW) experience high rates of HIV early in their sexual life course. We estimated the prevalence of HIV-associated vulnerabilities at first sex, and their association with lifetime gender-based violence (GBV) and HIV.

METHODS

We conducted a cross-sectional biobehavioral survey among AGYW (14-24 years) in Mombasa, Kenya in 2015. We compared the prevalence of first sex vulnerabilities across AGYW who self-identified as engaging in sex work (N = 408), transactional sex (N = 177), or casual sex (N = 714) and used logistic regression to identify age-adjusted associations between first sex vulnerabilities and outcomes (GBV after first sex; HIV).

RESULTS

The median age at first sex was 16 years (interquartile range 14-18). A total of 43.6% received gifts or money at first sex; 41.2% and 11.2% experienced a coerced and forced first sex, respectively. First sex vulnerabilities were generally more common among AGYW in sex work. GBV (prevalence 23.8%) and HIV (prevalence 5.6%) were associated with first sex before age 15 [GBV adjusted odds ratio (AOR) 1.4, 95% confidence interval (CI): 1.0 to 1.9; HIV AOR 1.9, 95% CI: 1.1 to 1.3]; before or within 1 year of menarche (GBV AOR 1.3, 95% CI: 1.0 to 1.7; HIV AOR 2.1, 95% CI: 1.3 to 3.6); and receipt of money (GBV AOR 1.9, 95% CI: 1.4 to 2.5; HIV AOR 2.0, 95% CI: 1.2 to 3.4).

CONCLUSIONS

HIV-associated vulnerabilities begin at first sex and potentially mediate an AGYW's trajectory of risk. HIV prevention programs should include structural interventions that reach AGYW early, and screening for a history of first sex vulnerabilities could help identify AGYW at risk of ongoing GBV and HIV.

The disconnect between individual-level and population-level HIV prevention benefits of antiretroviral treatment

In 2019, the HIV pandemic is growing and soon over 40 million people will be living with HIV. Effective population-based approaches to decrease HIV incidence are as relevant as ever given modest reductions observed over the past decade. Treatment as prevention is often heralded as the path to improve HIV outcomes and to reduce HIV incidence. Although treatment of an individual does eliminate onward transmission to serodifferent partners (undetectable=untransmittable or U=U), population-level observational and experimental data have not shown a similar effect with scale-up of treatment on reducing HIV incidence. This disconnect might be the result of little attention given to heterogeneities of HIV acquisition and transmission risks that exist in people at risk for and living with HIV, even in the most broadly generalised epidemics. Available data suggest that HIV treatment is treatment, HIV prevention is prevention, and specificity of HIV treatment approaches towards people at highest risk of onward transmission drives the intersection between the two. All people living with HIV deserve HIV treatment, but both more accurately estimating and optimising the potential HIV prevention effects of universal treatment approaches necessitates understanding who is being supported with treatment rather than a focus on treatment targets such as 90-90-90 or 95-95-95.

Bayesian Estimation of MSM Population Size in Côte d'Ivoire

Côte d'Ivoire has among the most generalized HIV epidemics in West Africa with an estimated half million people living with HIV. Across West Africa, key populations, including gay men and other men who have sex with men (MSM), are often disproportionately burdened with HIV due to specific acquisition and transmission risks. Quantifying population sizes of MSM at the subnational level is critical to ensuring evidence-based decisions regarding the scale and content of HIV prevention interventions. While survey-based direct estimates of MSM numbers are available in a few urban centers across Côte d'Ivoire, no data on MSM population size exists in other areas without any community group infrastructure to facilitate sufficient access to communities of MSM. The data are used in a Bayesian regression setup to produce estimates of the numbers of MSM in areas of Côte d'Ivoire prioritized in the HIV response. Our hierarchical model imputes missing covariates using geo-spatial information and allows for proper uncertainty quantification leading to confidence bounds for predicted MSM population size estimates. This process provided population size estimates where there are no empirical data, to guide the prioritization of further collection of empirical data on MSM and inform evidence-based scaling of HIV prevention and treatment programs for MSM across Côte d'Ivoire.

HIV-related data among key populations to inform evidence-based responses: protocol of a systematic review

BACKGROUND

Key populations who bear a disproportionate burden of HIV, including female sex workers, men who have sex with men, people who use drugs, transgender people, and incarcerated populations, have been understudied, especially in the context of broadly generalized HIV epidemics. Program and investment planning documents often do not take into account the data that do exist. Prior systematic reviews have been comprehensive, but lack sustainability and relevance over time. This review aims to synthesize all available data for key populations and present the data through an accessible, updatable user-friendly graphic interface. The outputs of this systematic review will serve as a resource for decision-makers, providing government stakeholders and donors with the tools to make evidence-based decisions for national planning.

METHODS

We will conduct a systematic review of data published or made available between January 1, 2006, and January 1, 2019, that captures the burden of HIV, both prevalence and incidence estimates, HIV prevention and treatment cascades, key population size estimates, experienced violence, consistent condom use, and engagement with healthcare systems for female sex workers, men who have sex with men, people who use drugs, transgender people, and incarcerated populations. A team of reviewers will use Covidence to conduct two independent reviews of both title/abstract and full text for each article. REDCap will be used for data abstraction and storage.

DISCUSSION

Findings from this systematic review and the development of the enhanced graphical interface to display data, along with ongoing efforts to build capacity among key stakeholders to better use and interpret available data, will help ensure that available epidemiologic data related to key populations can be appropriately used to guide large-scale HIV funding and programmatic responses.

SYSTEMATIC REVIEW REGISTRATION

PROPSERO CRD42016047259 .

The global response and unmet actions for HIV and sex workers

Female, male, and transgender sex workers continue to have disproportionately high burdens of HIV infection in low-income, middle-income, and high-income countries in 2018. 4 years since our Lancet Series on HIV and sex work, our updated analysis of the global HIV burden among female sex workers shows that HIV prevalence is unacceptably high at 10·4% (95% CI 9·5-11·5) and is largely unchanged. Comprehensive epidemiological data on HIV and antiretroviral therapy (ART) coverage are scarce, particularly among transgender women. Sustained coverage of treatment is markedly uneven and challenged by lack of progress on stigma and criminalisation, and sustained human rights violations. Although important progress has been made in biomedical interventions with pre-exposure prophylaxis and early ART feasibility and demonstration projects, limited coverage and retention suggest that sustained investment in community and structural interventions is required for sex workers to benefit from the preventive interventions and treatments that other key populations have. Evidence-based progress on full decriminalisation grounded in health and human rights-a key recommendation in our Lancet Series-has stalled, with South Africa a notable exception. Additionally, several countries have rolled back rights to sex workers further. Removal of legal barriers through the decriminalisation of sex work, alongside political and funding investments to support community and structural interventions, is urgently needed to reverse the HIV trajectory and ensure health and human rights for all sex workers.

Defining the population attributable fraction for infectious diseases

Background

The population attributable fraction (PAF) is used to quantify the contribution of a risk group to disease burden. For infectious diseases, high-risk individuals may increase disease risk for the wider population in addition to themselves; therefore methods are required to estimate the PAF for infectious diseases.

Methods

A mathematical model of disease transmission in a population with a high-risk group was used to compare existing approaches for calculating the PAF. We quantify when existing methods are consistent and when estimates diverge. We introduce a new method, based on the basic reproduction number, for calculating the PAF, which bridges the gap between existing methods and addresses shortcomings. We illustrate the methods with two examples of the contribution of badgers to bovine tuberculosis in cattle and the role of commercial sex in an HIV epidemic.

Results

We demonstrate that current methods result in irreconcilable PAF estimates, depending on how chains of transmission are categorized. Using two novel simple formulae for emerging and endemic diseases, we demonstrate that the largest differences occur when transmission in the general population is not self-sustaining. Crucially, some existing methods are not able to discriminate between multiple risk groups. We show that compared with traditional estimates, assortative mixing leads to a decreased PAF, whereas disassortative mixing increases PAF.

Conclusions

Recent methods for calculating the population attributable fraction (PAF) are not consistent with traditional approaches. Policy makers and users of PAF statistics should be aware of these differences. Our approach offers a straightforward and parsimonious method for calculating the PAF for infectious diseases.

Opportunities for Enhanced Strategic Use of Surveys, Medical Records, and Program Data for HIV Surveillance of Key Populations: Scoping Review

BACKGROUND

Normative guidelines from the World Health Organization recommend tracking strategic information indicators among key populations. Monitoring progress in the global response to the HIV epidemic uses indicators put forward by the Joint United Nations Programme on HIV/AIDS. These include the 90-90-90 targets that require a realignment of surveillance data, routinely collected program data, and medical record data, which historically have developed separately.

OBJECTIVE

The aim of this study was to describe current challenges for monitoring HIV-related strategic information indicators among key populations ((men who have sex with men [MSM], people in prisons and other closed settings, people who inject drugs, sex workers, and transgender people) and identify future opportunities to enhance the use of surveillance data, programmatic data, and medical record data to describe the HIV epidemic among key populations and measure the coverage of HIV prevention, care, and treatment programs.

METHODS

To provide a historical perspective, we completed a scoping review of the expansion of HIV surveillance among key populations over the past three decades. To describe current efforts, we conducted a review of the literature to identify published examples of SI indicator estimates among key populations. To describe anticipated challenges and future opportunities to improve measurement of strategic information indicators, particularly from routine program and health data, we consulted participants of the Third Global HIV Surveillance Meeting in Bangkok, where the 2015 World Health Organization strategic information guidelines were launched.

RESULTS

There remains suboptimal alignment of surveillance and programmatic data, as well as routinely collected medical records to facilitate the reporting of the 90-90-90 indicators for HIV among key populations. Studies (n=3) with estimates of all three 90-90-90 indicators rely on cross-sectional survey data. Programmatic data and medical record data continue to be insufficiently robust to provide estimates of the 90-90-90 targets for key populations.

CONCLUSIONS

Current reliance on more active data collection processes, including key population-specific surveys, remains warranted until the quality and validity of passively collected routine program and medical record data for key populations is optimized.

Changing Dynamics of HIV Transmission in Côte d'Ivoire: Modeling Who Acquired and Transmitted Infections and Estimating the Impact of Past HIV Interventions (1976-2015)

INTRODUCTION

Understanding the impact of past interventions and how it affected transmission dynamics is key to guiding prevention efforts. We estimated the population-level impact of condom, antiretroviral therapy (ART), and prevention of mother-to-child transmission activities on HIV transmission and the contribution of key risk factors on HIV acquisition and transmission.

METHODS

An age-stratified dynamical model of sexual and vertical HIV transmission among the general population, female sex workers (FSW), and men who have sex with men was calibrated to detailed prevalence and intervention data. We estimated the fraction of HIV infections averted by the interventions, and the fraction of incident infections acquired and transmitted by different populations over successive 10-year periods (1976-2015).

RESULTS

Overall, condom use averted 61% (95% credible intervals: 56%-66%) of all adult infections during 1987-2015 mainly because of increased use by FSW (46% of infections averted). In comparison, ART prevented 15% (10%-19%) of adult infections during 2010-2015. As a result, FSW initially (1976-1985) contributed 95% (91%-97%) of all new infections, declining to 19% (11%-27%) during 2005-2015. Older men and clients mixing with non-FSW are currently the highest contributors to transmission. Men who have sex with men contributed ≤4% transmissions throughout. Young women (15-24 years; excluding FSW) do not transmit more infections than they acquired.

CONCLUSIONS

Early increases in condom use, mainly by FSW, have substantially reduced HIV transmission. Clients of FSWs and older men have become the main source of transmission, whereas young women remain at increased risk. Strengthening prevention and scaling-up of ART, particularly to FSW and clients of female sex workers, is important.

The Incidence Patterns Model to Estimate the Distribution of New HIV Infections in Sub-Saharan Africa: Development and Validation of a Mathematical Model

BACKGROUND

Programmatic planning in HIV requires estimates of the distribution of new HIV infections according to identifiable characteristics of individuals. In sub-Saharan Africa, robust routine data sources and historical epidemiological observations are available to inform and validate such estimates.

METHODS AND FINDINGS

We developed a predictive model, the Incidence Patterns Model (IPM), representing populations according to factors that have been demonstrated to be strongly associated with HIV acquisition risk: gender, marital/sexual activity status, geographic location, "key populations" based on risk behaviours (sex work, injecting drug use, and male-to-male sex), HIV and ART status within married or cohabiting unions, and circumcision status. The IPM estimates the distribution of new infections acquired by group based on these factors within a Bayesian framework accounting for regional prior information on demographic and epidemiological characteristics from trials or observational studies. We validated and trained the model against direct observations of HIV incidence by group in seven rounds of cohort data from four studies ("sites") conducted in Manicaland, Zimbabwe; Rakai, Uganda; Karonga, Malawi; and Kisesa, Tanzania. The IPM performed well, with the projections' credible intervals for the proportion of new infections per group overlapping the data's confidence intervals for all groups in all rounds of data. In terms of geographical distribution, the projections' credible intervals overlapped the confidence intervals for four out of seven rounds, which were used as proxies for administrative divisions in a country. We assessed model performance after internal training (within one site) and external training (between sites) by comparing mean posterior log-likelihoods and used the best model to estimate the distribution of HIV incidence in six countries (Gabon, Kenya, Malawi, Rwanda, Swaziland, and Zambia) in the region. We subsequently inferred the potential contribution of each group to transmission using a simple model that builds on the results from the IPM and makes further assumptions about sexual mixing patterns and transmission rates. In all countries except Swaziland, individuals in unions were the single group contributing to the largest proportion of new infections acquired (39%-77%), followed by never married women and men. Female sex workers accounted for a large proportion of new infections (5%-16%) compared to their population size. Individuals in unions were also the single largest contributor to the proportion of infections transmitted (35%-62%), followed by key populations and previously married men and women. Swaziland exhibited different incidence patterns, with never married men and women accounting for over 65% of new infections acquired and also contributing to a large proportion of infections transmitted (up to 56%). Between- and within-country variations indicated different incidence patterns in specific settings.

CONCLUSIONS

It is possible to reliably predict the distribution of new HIV infections acquired using data routinely available in many countries in the sub-Saharan African region with a single relatively simple mathematical model. This tool would complement more specific analyses to guide resource allocation, data collection, and programme planning.