Positive impact of increases in condom use among female sex workers and clients in a medium HIV prevalence epidemic: modelling results from Project SIDA1/2/3 in Cotonou, Benin

The impact of past HIV interventions and diagnosis gaps on new HIV acquisitions, transmissions, and HIV-related deaths in Côte d'Ivoire, Mali, and Senegal

OBJECTIVES

To estimate the epidemiological impact of past HIV interventions and the magnitude and contribution of undiagnosed HIV among different risk groups on new HIV acquisitions in Côte d'Ivoire, Mali and Senegal.

DESIGN

HIV transmission dynamic models among the overall population and key populations [female sex workers (FSW), their clients, and MSM].

METHODS

Models were independently parameterized and calibrated for each set of country-specific demographic, behavioural, and epidemiological data. We estimated the fraction of new HIV infections over 2012-2021 averted by condom use and antiretroviral therapy (ART) uptake among key populations and non-key populations, the direct and indirect contribution of specific groups to new infections [transmission population-attributable fraction (tPAF)] over 2012-2021 due to prevention gaps, and the distribution of undiagnosed people with HIV (PWH) by risk group in January 2022 and their tPAF over 2022-2031.

RESULTS

Condom use and ART may have averted 81-88% of new HIV infections over 2012-2021 across countries, mostly due to condom use by key population. The tPAF of all key populations combined over 2012-2021 varied between 27% (Côte d'Ivoire) and 79% (Senegal). Male key populations (clients of FSW and MSM) contributed most to new infections (>60% in Mali and Senegal) owing to their higher HIV prevalence and larger prevention gaps. In 2022, men represented 56% of all PWH with an undiagnosed infection in Côte d'Ivoire (male key populations = 15%), 46% in Mali (male key populations = 23%), and 69% in Senegal (male key populations = 55%). If HIV testing and ART initiation rates remain at current levels, 20% of new HIV infections could be due to undiagnosed key populations living with HIV in Côte d'Ivoire over 2022-2031, 53% in Mali, and 65% in Senegal.

CONCLUSION

Substantial HIV diagnosis gaps remain in Western Africa, especially among male key populations. Addressing these gaps is key to impacting the HIV epidemics in the region and achieving the goal of ending AIDS by 2030.

Quantitative Methods Used to Evaluate Impact of Combination HIV Prevention Intervention: A Methodological Systematic Review

Combination HIV prevention aims to provide the right mix of biomedical, behavioral and structural interventions, and is considered the best approach to curb the HIV pandemic. The impact evaluation of combined HIV prevention intervention (CHPI) provides critical information for decision making. We conducted a systematic review of the literature to map the designs and methods used in these studies. We searched original articles indexed in Web of Science, Scopus and PubMed. Fifty-eight studies assessing the impact of CHPI on HIV transmission were included. Most of the studies took place in Asia or sub-Saharan Africa and were published from 2000 onward. We identified 36 (62.1%) quasi-experimental studies (posttest, pretest-posttest and nonequivalent group designs) and 22 (37.9%) experimental studies (randomized designs). The findings suggest that diverse methods are already rooted in CHPI impact evaluation practices as recommended but should be better reported. CHPI impact evaluation would benefit from more comprehensive approaches.

Predictive Factors of HIV-1 Drug Resistance and Its Distribution among Female Sex Workers in the Democratic Republic of the Congo (DRC)

The predictive factors of HIV-1 drug resistance and its distribution are poorly documented in female sex workers (FSWs) in the Democratic Republic of the Congo (DRC). However, the identification of predictive factors can lead to the development of improved and effective antiretroviral therapy (ART). The objective of the current study was to determine the predictive factors of HIV-1 drug resistance and its distribution based on FSWs in the studied regions in the Democratic Republic of the Congo (DRC). HIV-positive FSWs who were diagnosed as part of the DRC Integrated Biological and Behavioral Surveillance Survey (IBBS) were included in this study. A total of 325 FSWs participated. The HIV-1 viral load (VL) was measured according to the Abbott m2000sp and m2000rt protocols. The homogeneity chi-square test was conducted to determine the homogeneity of HIV-1 drug resistance distribution. Using a significance level of 0.05, multivariate analyses were performed to identify factors associated with HIV-1 drug resistance to ART. HIV drug resistance mutation (HIVDRM) distribution was homogeneous in the three study regions (p = 0.554) but differed based on the HIV-1 VLs of the FSWs. FSWs with high HIV-1 VLs harbored more HIVDRMs (p = 0.028) of predominantly pure HIV-1 strains compared with those that had low HIV-1 VLs. Sexually transmitted infection (STI) history (aOR [95%CI] = 8.51 [1.62, 44.74]), high HIV-1 VLs (aOR [95%CI] = 5.39 [1.09, 26.74]), and HIV-1-syphilis coinfection (aOR [95%CI] = 9.71 [1.84, 51.27]) were associated with HIV drug resistance among FSWs in the DRC. A history of STIs (e.g., abnormal fluid) in the 12 months prior to the survey, a high HIV-1 VL, and HIV-1-syphilis coinfection were associated with HIV-1 drug resistance among FSWs in the DRC. Efforts should be made to systematically test for other infections which increase the HIV-1 VL, in the case of HIV-1 coinfection, in order to maintain ART effectiveness across the DRC.

The impact of condom use on the HIV epidemic

Background: Condom promotion and supply was one the earliest interventions to be mobilized to address the HIV pandemic. Condoms are inexpensive and provide protection against transmission of HIV and other sexually transmitted diseases (STIs) as well as against unintended pregnancy. As many as 16 billion condoms may be used annually in all low- and middle-income countries (LMIC). In recent years the focus of HIV programs as been on testing and treatment and new technologies such as PrEP. Rates of condom use have stopped increasing short of UNAIDS targets and funding from donors is declining. Methods: We applied a mathematical HIV transmission model to 77 high HIV burden countries to estimate the number of HIV infections that would have occurred from 1990 to 2019 if condom use had remained at 1990 levels. Results: The results suggest that current levels of HIV would be five times higher without condom use and that the scale-up in condoms use averted about 117 million HIV infections. Conclusions: HIV programs should ensure that affordable condoms are consistently available and that the benefits of condom use are widely understood.

HIV Prevention and Treatment Cascades Among Female Sex Workers in Benin, West Africa

BACKGROUND

Benin has a long-standing history of HIV prevention programs aimed at female sex workers (FSWs). We used data from a national survey among FSWs (2017) to assess the prevention and care cascades in this population.

METHODS

Female sex workers were recruited through cluster sampling of sex work sites. A questionnaire was administered, and HIV tested. HIV-positive participants were asked to provide dried blood spots and were tested for antiretroviral and viral load. We assessed 2 prevention cascades (HIV testing and safer sex) and the treatment cascade, using a combination of self-reported and biological variables.

RESULTS

Mean age of the 1086 FSWs was 30 years. Half of them were Beninese, and two-thirds had a primary school education level or less. Almost all FSWs had ever heard of HIV/AIDS. More than half (79.1%) had ever been tested, and 84.1% of the latter had been tested in the last year. In the previous 6 months, 90.1% were exposed to prevention messages. Women exposed to any HIV prevention message reported a higher level of consistent condom use in the last month (69.0%) than those who were not (48.5%, P < 0.0001). HIV prevalence was 7.7%. Among HIV-positive women, 60.6% knew their status; among those, 90.5% were on antiretroviral and 81.8% of them had a suppressed viral load.

CONCLUSIONS

Despite long-standing HIV prevention programs for FSWs, the prevention indicators were often low. Linkage to care was good, viral suppression was suboptimal, but knowledge of HIV-positive status was low. Exposing women to prevention messages is necessary, as to increase HIV testing.

Assessing the Potential Impact of Disruptions Due to COVID-19 on HIV Among Key and Lower-Risk Populations in the Largest Cities of Cameroon and Benin

BACKGROUND

The COVID-19 pandemic indirectly impacts HIV epidemiology in Central/West Africa. We estimated the potential impact of COVID-19-related disruptions to HIV prevention/treatment services and sexual partnerships on HIV incidence and HIV-related deaths among key populations including female sex workers (FSW), their clients, men who have sex with men, and overall.

SETTING

Yaoundé (Cameroon) and Cotonou (Benin).

METHODS

We used mathematical models of HIV calibrated to city population-specific and risk population-specific demographic/behavioral/epidemic data. We estimated the relative change in 1-year HIV incidence and HIV-related deaths for various disruption scenarios of HIV prevention/treatment services and decreased casual/commercial partnerships, compared with a scenario without COVID-19.

RESULTS

A 50% reduction in condom use in all partnerships over 6 months would increase 1-year HIV incidence by 39%, 42%, 31%, and 23% among men who have sex with men, FSW, clients, and overall in Yaoundé, respectively, and 69%, 49%, and 23% among FSW, clients, and overall, respectively, in Cotonou. Combining a 6-month interruption of ART initiation and 50% reduction in HIV prevention/treatment use would increase HIV incidence by 50% and HIV-related deaths by 20%. This increase in HIV infections would be halved by a simultaneous 50% reduction in casual and commercial partnerships.

CONCLUSIONS

Reductions in condom use after COVID-19 would increase infections among key populations disproportionately, particularly FSW in Cotonou, who need uninterrupted condom provision. Disruptions in HIV prevention/treatment services have the biggest impacts on HIV infections and deaths overall, only partially mitigated by equal reductions in casual/commercial sexual partnerships. Maintaining ART provision must be prioritized to minimize short-term excess HIV-related deaths.

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.

The impact of condom use on the HIV epidemic

Background: Condom promotion and supply was one the earliest interventions to be mobilized to address the HIV pandemic. Condoms are inexpensive and provide protection against transmission of HIV and other sexually transmitted diseases (STIs) as well as against unintended pregnancy. As many as 16 billion condoms may be used annually in all low- and middle-income countries (LMIC). In recent years the focus of HIV programs as been on testing and treatment and new technologies such as PrEP. Rates of condom use have stopped increasing short of UNAIDS targets and funding from donors is declining. Methods: We applied a mathematical HIV transmission model to 77 high HIV burden countries to estimate the number of HIV infections that would have occurred from 1990 to 2019 if condom use had remained at 1990 levels. Results: The results suggest that current levels of HIV would be five times higher without condom use and that the scale-up in condoms use averted about 117 million HIV infections. Conclusions: HIV programs should ensure that affordable condoms are consistently available and that the benefits of condom use are widely understood.

Quantifying the Evolving Contribution of HIV Interventions and Key Populations to the HIV Epidemic in Yaoundé, Cameroon

BACKGROUND

Key populations (KP) including men who have sex with men (MSM), female sex workers (FSW), and their clients are disproportionately affected by HIV in Sub-Saharan Africa. We estimated the evolving impact of past interventions and contribution of unmet HIV prevention/treatment needs of key populations and lower-risk groups to HIV transmission.

SETTING

Yaoundé, Cameroon.

METHODS

We parametrized and fitted a deterministic HIV transmission model to Yaoundé-specific demographic, behavioral, HIV, and intervention coverage data in a Bayesian framework. We estimated the fraction of incident HIV infections averted by condoms and antiretroviral therapy (ART) and the fraction of all infections over 10-year periods directly and indirectly attributable to sex within and between each risk group.

RESULTS

Condom use and ART together may have averted 43% (95% uncertainty interval: 31-54) of incident infections over 1980-2018 and 72% (66-79) over 2009-2018. Most onward transmissions over 2009-2018 stemmed from sex between lower-risk individuals [47% (32-61)], clients [37% (23-51)], and MSM [35% (20-54)] with all their partners. The contribution of commercial sex decreased from 25% (8-49) over 1989-1998 to 8% (3-22) over 2009-2018, due to higher intervention coverage among FSW.

CONCLUSION

Condom use and recent ART scale-up mitigated the HIV epidemic in Yaoundé and changed the contribution of different partnerships to onward transmission over time. Findings highlight the importance of prioritizing HIV prevention and treatment for MSM and clients of FSW whose unmet needs now contribute most to onward transmission, while maintaining services that successfully reduced transmissions in the context of commercial sex.

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.

Mathematical Model Impact Analysis of a Real-Life Pre-exposure Prophylaxis and Treatment-As-Prevention Study Among Female Sex Workers in Cotonou, Benin

BACKGROUND

Daily pre-exposure prophylaxis (PrEP) and treatment-as-prevention (TasP) reduce HIV acquisition and transmission risk, respectively. A demonstration study (2015-2017) assessed TasP and PrEP feasibility among female sex workers (FSW) in Cotonou, Benin.

SETTING

Cotonou, Benin.

METHODS

We developed a compartmental HIV transmission model featuring PrEP and antiretroviral therapy (ART) among the high-risk (FSW and clients) and low-risk populations, calibrated to historical epidemiological and demonstration study data, reflecting observed lower PrEP uptake, adherence and retention compared with TasP. We estimated the population-level impact of the 2-year study and several 20-year intervention scenarios, varying coverage and adherence independently and together. We report the percentage [median, 2.5th-97.5th percentile uncertainty interval (95% UI)] of HIV infections prevented comparing the intervention and counterfactual (2017 coverages: 0% PrEP and 49% ART) scenarios.

RESULTS

The 2-year study (2017 coverages: 9% PrEP and 83% ART) prevented an estimated 8% (95% UI 6-12) and 6% (3-10) infections among FSW over 2 and 20 years, respectively, compared with 7% (3-11) and 5% (2-9) overall. The PrEP and TasP arms prevented 0.4% (0.2-0.8) and 4.6% (2.2-8.7) infections overall over 20 years, respectively. Twenty-year PrEP and TasP scale-ups (2035 coverages: 47% PrEP and 88% ART) prevented 21% (17-26) and 17% (10-27) infections among FSW, respectively, and 5% (3-10) and 17% (10-27) overall. Compared with TasP scale-up alone, PrEP and TasP combined scale-up prevented 1.9× and 1.2× more infections among FSW and overall, respectively.

CONCLUSIONS

The demonstration study impact was modest, and mostly from TasP. Increasing PrEP adherence and coverage improves impact substantially among FSW, but little overall. We recommend TasP in prevention packages.

Estimating the contribution of key populations towards HIV transmission in South Africa

INTRODUCTION

In generalized epidemic settings, there is insufficient understanding of how the unmet HIV prevention and treatment needs of key populations (KPs), such as female sex workers (FSWs) and men who have sex with men (MSM), contribute to HIV transmission. In such settings, it is typically assumed that HIV transmission is driven by the general population. We estimated the contribution of commercial sex, sex between men, and other heterosexual partnerships to HIV transmission in South Africa (SA).

METHODS

We developed the "Key-Pop Model"; a dynamic transmission model of HIV among FSWs, their clients, MSM, and the broader population in SA. The model was parameterized and calibrated using demographic, behavioural and epidemiological data from national household surveys and KP surveys. We estimated the contribution of commercial sex, sex between men and sex among heterosexual partnerships of different sub-groups to HIV transmission over 2010 to 2019. We also estimated the efficiency (HIV infections averted per person-year of intervention) and prevented fraction (% IA) over 10-years from scaling-up ART (to 81% coverage) in different sub-populations from 2020.

RESULTS

Sex between FSWs and their paying clients, and between clients with their non-paying partners contributed 6.9% (95% credibility interval 4.5% to 9.3%) and 41.9% (35.1% to 53.2%) of new HIV infections in SA over 2010 to 2019 respectively. Sex between low-risk groups contributed 59.7% (47.6% to 68.5%), sex between men contributed 5.3% (2.3% to 14.1%) and sex between MSM and their female partners contributed 3.7% (1.6% to 9.8%). Going forward, the largest population-level impact on HIV transmission can be achieved from scaling up ART to clients of FSWs (% IA = 18.2% (14.0% to 24.4%) or low-risk individuals (% IA = 20.6% (14.7 to 27.5) over 2020 to 2030), with ART scale-up among KPs being most efficient.

CONCLUSIONS

Clients of FSWs play a fundamental role in HIV transmission in SA. Addressing the HIV prevention and treatment needs of KPs in generalized HIV epidemics is central to a comprehensive HIV response.

Prevalence and characteristics of HIV infection among female sex workers in Lubumbashi, Democratic Republic of Congo

Introduction

female sex workers (FSWs) are considered a high-risk group for acquiring HIV infection due to their HIV prevalence estimated to be 10-20 times higher than in woman in the general population. This study aimed to determine the prevalence and risk factors of HIV among female sex workers (FSWs) in Lubumbashi.

Methods

a cross-sectional study was conducted among FSWs presenting for the first time at the sexually transmitted infections (STIs) clinic of Katuba, Lubumbashi, between April 2016 and December 2017. Information on the participants´ socio-demographic characteristics, sexual behaviors, and HIV serology results were collated and analyzed using a multiple logistic regression to identify factors associated to HIV infection among FSWs.

Results

information on 1555 sex workers was analysed in this study, the prevalence of HIV was 8.2%. The median age of the participants was 26 years (IQR: 21-34). Of the 127 HIV positive sex workers, 74% have been in the business for two years or less, 97% sell sex as their main income, 74% have more than 5 sexual intercourses per week, 95% reported using condom, 73% reported having history of STIs, 70% reported using alcohol before sex and 97% reported having three or more sexual partners per week. After adjusting for potentials cofounders, Age, Sex work as main income, years of selling sex, condom use, and alcohol use before sex were found to have a significant effect on HIV infection among sex workers.

Conclusion

these findings highlight the vulnerability of FSWs to HIV infection and the necessity of immediate interventions to strengthen HIV prevention through behavioral change strategies and making available Pre-exposure Prophylaxis (PrEP) for FSWs in Lubumbashi.

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.

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.

Lifetime experiences of gender-based violence, depression and condom use among female sex workers in Cameroon

BACKGROUND

In general populations, consistent data highlight the relationships among violence, HIV risk behavior and depression; however, these patterns are not well understood among female sex workers (FSWs). We examined the relationship between FSWs' experiences with sexual violence and consistent condom use as a key HIV risk behavior and explored mental health as a potential mediator.

METHODS

In total, 2,165 FSWs were recruited via respondent-driven sampling in Cameroon in 2016. The women answered questions about violence, condom use and mental health.

RESULTS

Inconsistent condom use with clients was reported by 23.5% of participants (508/2,165). Lifetime sexual violence was prevalent with 33.0% (713/2,163) of participants. Almost 50% (1,067/2,143) of respondents had some level of depression. Sexual violence was significantly associated with inconsistent condom use (adjusted risk ratio (aRR) 1.4, 95% confidence interval (CI) (1.2-1.6)). Of FSWs with no depression, 24.9% (267/1,071) reported sexual violence, versus 56.1% (32/57) of respondents with severe depression (p < .01). Severe depression significantly increased risk of condomless sex (aRR 1.8, 95% CI (1.3-2.6)); in mediation analysis, both sexual violence and severe depression remained significant predictors of condomless sex (aRR 1.4, 95% CI (1.2, 1.6) and aRR 1.7, 95% CI (1.2-2.4), respectively). Depression did not mediate the relationship between sexual violence and condom use.

CONCLUSION

Sexual violence and depression are prevalent and independently associated with condom nonuse with clients among FSWs in Cameroon. Results highlight the need for interventions to address mental health as well as gender-based violence for FSWs.

Recruitment of Female Sex Workers in HIV Prevention Trials: Can Efficacy Endpoints Be Reached More Efficiently?

BACKGROUND/SETTING

Randomized controlled trials (RCTs) of HIV biomedical prevention interventions often enroll participants with varying levels of HIV exposure, including people never exposed to HIV. We assessed whether enrolling larger proportion of participants with consistently high exposure to HIV, such as female sex workers (FSWs), might reduce trial duration and improve the accuracy of product efficacy estimates in future HIV prevention trials.

METHODS

We used an individual-based stochastic model to simulate event-driven RCTs of an HIV prevention intervention providing 80% reduction in susceptibility per act under different proportions of FSW enrolled. A 5% annual dropout rate was assumed for both FSW and non-FSW in our main scenario, but rates of up to 50% for FSW were also explored.

RESULTS

Enrolling 20% and 50% FSW reduced the median-simulated trial duration from 30 months with 0% FSW enrolled to 22 months and 17 months, respectively. Estimated efficacy increased from 71% for RCTs without FSW to 74% and 76% for RCTs with 20% and 50% FSW enrolled, respectively. Increasing the FSW dropout rate to 50% increased the duration of RCTs by 1-2 months on average and preserved the gain in estimated efficacy.

CONCLUSIONS

Despite the potential logistical challenges of recruiting and retaining FSW, trialists should revisit the idea of enrolling FSW in settings where HIV incidence among FSW is higher than among non-FSW. Our analysis suggests that enrolling FSW would increase HIV incidence, reduce trial duration, and improve efficacy estimates, even if the annual dropout rate among FSW participants is high.

Early antiretroviral therapy and daily pre-exposure prophylaxis for HIV prevention among female sex workers in Cotonou, Benin: a prospective observational demonstration study

INTRODUCTION

In sub-Saharan Africa, HIV prevalence remains high, especially among key populations. In such situations, combination prevention including clinical, behavioural, structural and biological components, as well as adequate treatment are important. We conducted a demonstration project at the Dispensaire IST, a clinic dedicated to female sex workers (FSWs) in Cotonou, on early antiretroviral therapy (E-ART, or immediate "test-and-treat") and pre-exposure prophylaxis (PrEP). We present key indicators such as uptake, retention and adherence.

METHODS

In this prospective observational study, we recruited FSWs from October 4th 2014 to December 31st 2015 and followed them until December 31st 2016. FSWs were provided with daily tenofovir disoproxil fumarate/emtricitabine (Truvada® ) for PrEP or received a first-line antiretroviral regimen as per Benin guidelines. We used generalized estimating equations to assess trends in adherence and sexual behaviour.

RESULTS

Among FSWs in the catchment area, HIV testing coverage within the study framework was 95.5% (422/442). At baseline, HIV prevalence was 26.3% (111/422). Among eligible FSWs, 95.5% (105/110) were recruited for E-ART and 88.3% (256/290) for PrEP. Overall retention at the end of the study was 59.0% (62/105) for E-ART and 47.3% (121/256) for PrEP. Mean (±SD) duration of follow-up was 13.4 (±7.9) months for E-ART and 11.8 (±7.9) months for PrEP. Self-reported adherence was over 90% among most E-ART participants. For PrEP, adherence was lower and the proportion with 100% adherence decreased over time from 78.4% to 56.7% (p-trend < 0.0001). During the 250.1 person-years of follow-up among PrEP initiators, two seroconversions occurred (incidence 0.8/100 person-years (95% confidence interval: 0.3 to 1.9/100 person-years)). The two seroconverters had stopped using PrEP for at least six months before being found HIV-infected. In both groups, there was no evidence of reduced condom use.

CONCLUSIONS

This study provides data on key indicators for the integration of E-ART and PrEP into the HIV prevention combination package already offered to FSWs in Benin. PrEP may be more useful as an individual intervention for adherent FSWs rather than a specific public health intervention. E-ART was a more successful intervention in terms of retention and adherence and is now offered to all key populations in Benin.

STUDY REGISTRATION

ClinicalTrials.gov NCT02237.

Estimating the contribution of key populations towards the spread of HIV in Dakar, Senegal

INTRODUCTION

Key populations including female sex workers (FSW) and men who have sex with men (MSM) bear a disproportionate burden of HIV. However, the role of focusing prevention efforts on these groups for reducing a country's HIV epidemic is debated. We estimate the extent to which HIV transmission among FSW and MSM contributes to overall HIV transmission in Dakar, Senegal, using a dynamic assessment of the population attributable fraction (PAF).

METHODS

A dynamic transmission model of HIV among FSW, their clients, MSM and the lower-risk adult population was parameterized and calibrated within a Bayesian framework using setting-specific demographic, behavioural, HIV epidemiological and antiretroviral treatment (ART) coverage data for 1985 to 2015. We used the model to estimate the 10-year PAF of commercial sex between FSW and their clients, and sex between men, to overall HIV transmission (defined as the percentage of new infections prevented when these modes of transmission are removed). In addition, we estimated the prevention benefits associated with historical increases in condom use and ART uptake, and impact of further increases in prevention and treatment.

RESULTS

The model projections suggest that unprotected sex between men contributed to 42% (2.5 to 97.5th percentile range 24 to 59%) of transmissions between 1995 and 2005, increasing to 64% (37 to 79%) from 2015 to 2025. The 10-year PAF of commercial sex is smaller, diminishing from 21% (7 to 39%) in 1995 to 14% (5 to 35%) in 2015. Without ART, 49% (32 to 71%) more HIV infections would have occurred since 2000, when ART was initiated, whereas without condom use since 1985, 67% (27 to 179%) more HIV infections would have occurred, and the overall HIV prevalence would have been 60% (29 to 211%) greater than what it is now. Further large decreases in HIV incidence (68%) can be achieved by scaling up ART in MSM to 74% coverage and reducing their susceptibility to HIV by two-thirds through any prevention modality.

CONCLUSIONS

Unprotected sex between men may be an important contributor to HIV transmission in Dakar, due to suboptimal coverage of evidence-informed interventions. Although existing interventions have effectively reduced HIV transmission among adults, it is crucial that further strategies address the unmet need among MSM.

HIV among Female Sex Workers in Five Cities in Burkina Faso: A Cross-Sectional Baseline Survey to Inform HIV/AIDS Programs

Background

Female sex workers (FSWs) are considered a vulnerable population for HIV infection and a priority for HIV/AIDS response programs. This study aimed to determine HIV prevalence among FSWs in five cities in Burkina Faso.

Methods

FSWs aged 18 and older were recruited using respondent driven sampling (RDS) in five cities (Ouagadougou, Bobo-Dioulasso, Koudougou, Ouahigouya, and Tenkodogo) in Burkina Faso from 2013 to 2014. HIV testing was performed using the HIV testing national algorithm. We conducted bivariate and multivariate logistic regression analysis to assess correlates of HIV in all cities combined (not RDS-adjusted).

Results

Among Ouagadougou, Koudougou, and Ouahigouya FSWs, RDS-adjusted HIV prevalence was 13.5% (95% Confidence Interval [CI]: 9.6-18.7), 13.3% (95% CI: 7.6-22.4), and 13.0% (95% CI: 7.6-21.3), respectively, compared to 30.1% (95% CI: 25.5-35.1) among Bobo-Dioulasso FSWs. Factors associated with HIV infection were age (adjusted odds ratio [aOR] = 7.84 95% CI: 3.78-16.20), being married or cohabitating (aOR = 2.43, 95% CI: 1.31-4.49), and history of pregnancy (aOR = 5.24, 95% CI: 1.44-18.97).

Conclusion

These results highlight the need to strengthen HIV prevention among FSWs, through behavior change strategies, and improve access to sexual and reproductive health services.

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.

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

In the context of generalized human immunodeficiency virus (HIV) epidemics, there has been limited recent investment in HIV surveillance and prevention programming for key populations including female sex workers. Often implicit in the decision to limit investment in these epidemic settings are assumptions including that commercial sex is not significant to the sustained transmission of HIV, and HIV interventions designed to reach "all segments of society" will reach female sex workers and clients. Emerging empiric and model-based evidence is challenging these assumptions. This article highlights the frameworks and estimates used to characterize the role of sex work in HIV epidemics as well as the relevant empiric data landscape on sex work in generalized HIV epidemics and their strengths and limitations. Traditional approaches to estimate the contribution of sex work to HIV epidemics do not capture the potential for upstream and downstream sexual and vertical HIV transmission. Emerging approaches such as the transmission population attributable fraction from dynamic mathematical models can address this gap. To move forward, the HIV scientific community must begin by replacing assumptions about the epidemiology of generalized HIV epidemics with data and more appropriate methods of estimating the contribution of unprotected sex in the context of sex work.

Getting the balance right: Scaling-up treatment and prevention

The goals of the international response to control the HIV epidemic include high antiretroviral therapy (ART) coverage with HIV viral suppression, as well as reduction of new infections. ART use at individual and population levels reduces HIV morbidity and mortality and likely reduces HIV incidence. HIV viral suppression requires high levels of ART adherence, which necessitates support through behavioural and structural interventions to optimise effectiveness of the use of ART for prevention. Many people living with HIV remain unaware that they are HIV-infected, and HIV transmission risk is high during early infection, therefore ART expansion should be accompanied by other interventions in order to achieve the promise of treatment for prevention. Biomedical and behavioural prevention efforts focused on HIV-uninfected individuals at substantial risk of HIV acquisition are also needed to control the epidemic. Maintaining prevention programming is essential during the scale up of ART to reduce HIV transmission.

Comparing the impact of increasing condom use or HIV pre-exposure prophylaxis (PrEP) use among female sex workers

In many settings, interventions targeting female sex workers (FSWs) could significantly reduce the overall transmission of HIV. To understand the role HIV pre-exposure prophylaxis (PrEP) could play in controlling HIV transmission amongst FSWs, it is important to understand how its impact compares with scaling-up condom use-one of the proven HIV prevention strategies for FSWs. It is important to remember that condoms also have other benefits such as reducing the incidence of sexually transmitted infections and preventing pregnancy. A dynamic deterministic model of HIV transmission amongst FSWs, their clients and other male partners (termed 'pimps') was used to compare the protection provided by PrEP for HIV-negative FSWs with FSWs increasing their condom use with clients and/or pimps. For different HIV prevalence scenarios, levels of pimp interaction, and baseline condom use, we estimated the coverage of PrEP that gives the same reduction in endemic FSW HIV prevalence or HIV infections averted as different increases in condom use. To achieve the same impact on FSW HIV prevalence as increasing condom use by 1%, the coverage of PrEP has to increase by >2%. The relative impact of PrEP increases for scenarios where pimps contribute to HIV transmission, but not greatly, and decreases with higher baseline condom use. In terms of HIV infections averted over 10 years, the relative impact of PrEP compared to condoms was reduced, with a >3% increase in PrEP coverage achieving the same impact as a 1% increase in condom use. Condom promotion interventions should remain the mainstay HIV prevention strategy for FSWs, with PrEP only being implemented once condom interventions have been maximised or to fill prevention gaps where condoms cannot be used.

Feasible, Efficient and Necessary, without Exception - Working with Sex Workers Interrupts HIV/STI Transmission and Brings Treatment to Many in Need

BACKGROUND AND OVERVIEW

High rates of partner change in sex work-whether in professional, 'transactional' or other context-disproportionately drive transmission of HIV and other sexually transmitted infections. Several countries in Asia have demonstrated that reducing transmission in sex work can reverse established epidemics among sex workers, their clients and the general population. Experience and emerging research from Africa reaffirms unprotected sex work to be a key driver of sexual transmission in different contexts and regardless of stage or classification of HIV epidemic. This validation of the epidemiology behind sexual transmission carries an urgent imperative to realign prevention resources and scale up effective targeted interventions in sex work settings, and, given declining HIV resources, to do so efficiently. Eighteen articles in this issue highlight the importance and feasibility of such interventions under four themes: 1) epidemiology, data needs and modelling of sex work in generalised epidemics; 2) implementation science addressing practical aspects of intervention scale-up; 3) community mobilisation and 4) the treatment cascade for sex workers living with HIV.

CONCLUSION

Decades of empirical evidence, extended by analyses in this collection, argue that protecting sex work is, without exception, feasible and necessary for controlling HIV/STI epidemics. In addition, the disproportionate burden of HIV borne by sex workers calls for facilitated access to ART, care and support. The imperative for Africa is rapid scale-up of targeted prevention and treatment, facilitated by policies and action to improve conditions where sex work takes place. The opportunity is a wealth of accumulated experience working with sex workers in diverse settings, which can be tapped to make up for lost time. Elsewhere, even in countries with strong interventions and services for sex workers, an emerging challenge is to find ways to sustain them in the face of declining global resources.

HIV prevention and care services for female sex workers: efficacy of a targeted community-based intervention in Burkina Faso

INTRODUCTION

Although interventions to control HIV among high-risk groups such as female sex workers (FSW) are highly recommended in Africa, the contents and efficacy of these interventions are unclear. We therefore designed a comprehensive dedicated intervention targeting young FSW and assessed its impact on HIV incidence in Burkina Faso.

METHODS

Between September 2009 and September 2011 we conducted a prospective, interventional cohort study of FSW aged 18 to 25 years in Ouagadougou, with quarterly follow-up for a maximum of 21 months. The intervention combined prevention and care within the same setting, consisting of peer-led education sessions, psychological support, sexually transmitted infections and HIV care, general routine health care and reproductive health services. At each visit, behavioural characteristics were collected and HIV, HSV-2 and pregnancy were tested. We compared the cohort HIV incidence with a modelled expected incidence in the study population in the absence of intervention, using data collected at the same time from FSW clients.

RESULTS

The 321 HIV-uninfected FSW enrolled in the cohort completed 409 person-years of follow-up. No participant seroconverted for HIV during the study (0/409 person-years), whereas the expected modelled number of HIV infections were 5.05/409 person-years (95% CI, 5.01-5.08) or 1.23 infections per 100 person-years (p=0.005). This null incidence was related to a reduction in the number of regular partners and regular clients, and by an increase in consistent condom use with casual clients (adjusted odds ratio (aOR)=2.19; 95% CI, 1.16-4.14, p=0.01) and with regular clients (aOR=2.18; 95% CI, 1.26-3.76, p=0.005).

CONCLUSIONS

Combining peer-based prevention and care within the same setting markedly reduced the HIV incidence among young FSW in Burkina Faso, through reduced risky behaviours.

A cross-sectional study to evaluate factors related to condom use with commercial sexual partners in workers from Ecuadorian companies

Background

Unprotected intercourse with sex workers is one of the major risk factors for HIV infection. Consistent condom use is a prerequisite to lower the incidence of HIV.

Methods

We assessed the prevalence of condom use and its determinants among company workers engaged with commercial sexual partners in Ecuador. The study was based on a random sample of 115 companies and 1,732 workers stratified by province and working sector and utilized the “Behavioral Surveillance Surveys – Adult questionnaire” developed by Family Health International.

Results

Of the 1,561 sexually active workers, 311 (19.9 %) reported having intercourse with sex workers. Among them 25.9 % did not use a condom at the last sexual intercourse. As for condom use frequency over the last 12 months, 29/208 (13.9 %) reported never, 23 (11.1 %) sometimes, 24 (11.5 %) almost every time and 132 (63.5 %) every time. Factors adversely affecting condom use frequency over the last 12 months were female gender (OR = 4.56, 95 % CI: 1.45-14.4), older age (OR = 1.07, 95 % CI: 1.03-1.10), low educational level (OR = 4.69, 95 % CI: 1.95-11.3) and married workers living with spouse (OR = 7.66, 95 % CI: 3.08-19.1). By contrast, factors such as age at first sexual intercourse, job category, HIV transmission and prevention measure knowledge, single workers, previous exposure to HIV intervention programs and having a casual sexual partner were not affecting condom use frequency. When considering condom use during the last sexual intercourse or during the past 12 months with commercial sexual partners, results were similar.

Conclusions

Workers with low education, older age, female gender and those married living with their spouse should be targeted for specific educational interventions.

[Clinical and immunological profile of HIV-infected patients at the initiation of antiretroviral therapy in Douala]

The aim of this study was to describe the clinical and immunological profile of patients infected with HIV after initiation of antiretroviral therapy. Sociodemographic characteristics, clinical and immunological patients were recorded. Chi square test and Mann-Whitney were used to compare variables. The multivariate regression model identified risk factors. So that, 936 (56.2%) patients were in stages III and IV of the WHO and 65.2% at an advanced stage of the disease. Factors associated with initiation at an advanced stage, were male sex (p = 0.007) and time to diagnosis (p = 0.005). In 2/3 cases, treatment is started at an advanced stage of disease. It is therefore important to intensify awareness campaigns for early detection and encourage patients to ensure regular medical follow-up screening.

Risk perception of sexually transmitted infections and HIV in Nigerian commercial sex workers in Barcelona: a qualitative study

OBJECTIVE

This study aimed to determine in detail the risk perception of sexually transmitted infections (STIs) and HIV, and the contextual circumstances, in Nigerian commercial sex workers (CSWs) in Barcelona.

DESIGN

A qualitative study with a phenomenological approach.

SETTING

Raval area in Barcelona.

PARTICIPANTS

8 CSWs working in Barcelona.

METHODS

A phenomenological study was carried out with Nigerian CSWs in Barcelona. Sampling was theoretical, taking into account: different age ranges; women with and without a partner; women with and without children; and women participating or not in STI/HIV-prevention workshops. Information was obtained by means of eight semistructured individual interviews. An interpretative content analysis was conducted by four analysts.

RESULTS

Illegal immigrant status, educational level, financial situation and work, and cultural context had mixed effects on CSW knowledge of, exposure to, and prevention and treatment of STI and HIV. CSWs were aware of the higher risk of STI associated with their occupation. They identified condoms as the best preventive method and used them during intercourse with clients. They also implemented other preventive behaviours such as personal hygiene after intercourse. Control of sexual services provided, health education and healthcare services had a positive effect on decreasing exposure and better management of STI/HIV.

CONCLUSIONS

Nigerian CSWs are a vulnerable group because of their poor socioeconomic status. The perception of risk in this group and their preventive behaviours are based on personal determinants, beliefs and experiences from their home country and influences from the host country. Interventions aimed at CSWs must address knowledge gaps, risk behaviours and structural elements.

Potential impact of existing interventions and of antiretroviral use in female sex workers on transmission of HIV in Burkina Faso: a modeling study

BACKGROUND

The impact and cost-effectiveness of antiretroviral treatment (ART) as prevention is likely to vary depending on the local context. Burkina Faso has a concentrated mature HIV epidemic where female sex workers (FSW) are thought to have driven HIV transmission.

METHODS

A dynamic HIV transmission model was developed using data from the Yerelon FSW cohort in Bobo-Dioulasso and population surveys. Compared with current ART provision [status quo (SQ)], the model estimated the proportion of HIV infections averted or incremental life-years gained per additional person-year of ART over 20 years for ART targeting different subgroups or expanding eligibility to all HIV-infected individuals compared with SQ.

RESULTS

Modeling suggests that condom use within commercial sex has averted 40% of past HIV infections. Continuing SQ averts 35%-47% of new infections over 20 years compared with no ART. Expanding ART eligibility to all HIV-infected individuals and increasing recruitment (80% per year) could avert a further 65% of new infections, whereas targeting full-time FSW or all FSWs achieved less impact but was more efficient in terms of life-years gained per 100 person-years of ART. Local HIV elimination is possible with expanded ART provision to FSWs but requires condom use within commercial sex to be maintained at high levels.

CONCLUSIONS

Increasing FSW recruitment onto ART could be a highly efficient method for reducing HIV transmission in concentrated epidemic settings but should not be undertaken at the expense of existing interventions for FSWs. Specialized clinics providing multiple interventions for FSWs should be a fundamental component of prevention in concentrated epidemics.

What really is a concentrated HIV epidemic and what does it mean for West and Central Africa? Insights from mathematical modeling

BACKGROUND

HIV epidemics have traditionally been classified as "concentrated" among key populations if overall HIV prevalence was below 1% and as "generalized" otherwise. We aimed to objectively determine the utility of this classification by determining how high overall HIV prevalence can reach in epidemics driven by unprotected sex work (SW) and how estimates of the contribution of SW to HIV transmission changes over time in these epidemics.

METHODS

We developed a deterministic model of HIV transmission specific to West and Central Africa to simulate 1000 synthetic HIV epidemics, where SW is the sole behavioral driver that sustains HIV in the population (ie, truly concentrated epidemics), and it is based on a systematic extraction of model parameters specific to West and Central Africa. We determined the range of plausible HIV prevalence in the total population over time and calculated the population attributable fraction (PAF) of SW over different time periods.

RESULTS

In 1988 and 2008, HIV prevalence across the 1000 synthetic concentrated HIV epidemics ranged (5th-95th percentile) between 0.1%-4.2% and 0.1%-2.8%, respectively. The maximum HIV prevalence peaked at 12%. The PAF of SW measured from 2008 over 1 year was <5%-18% compared with 16%-59% over 20 years in these SW-driven epidemics.

CONCLUSIONS

Even high HIV-prevalence epidemics can be driven by unprotected SW and therefore concentrated. Overall, HIV prevalence and the short-term PAF are poor makers of underlying transmission dynamics and underestimate the role of SW in HIV epidemics and thus should not be used alone to inform HIV programs.