The potential impact and cost of focusing HIV prevention on young women and men: A modeling analysis in western Kenya

Policies and Practices Facilitating Access to and Uptake of HIV Testing Services among Adolescents in Sub-Sahara Africa: A Narrative Review

PURPOSE OF REVIEW

Expanding access to HIV testing services and linking newly diagnosed positive adolescents to antiretroviral therapy is critical to epidemic control. However, testing coverage and treatment initiation rates continue to lag behind adult counterparts. This article synthesizes evidence on facilitative policies and service delivery practices focused on adolescents to inform programming.

RECENT FINDINGS

Our narrative review found that national policies are growing more adolescent-inclusive but barriers around the age of consent, waiver frameworks and dissemination constrain translate into practice. Facility-based provider-initiated testing through integrated sexual health services and dedicated youth centres demonstrates uptake effectiveness if confidentiality and youth-friendly adaptations are assured. Supportive policies, youth-responsive adaptations across testing models and strengthening age-disaggregated monitoring are vital to improving adolescents' engagement across the HIV testing and treatment cascade. Further implementation research is imperative to expand the reach of adolescent HIV testing in sub-Saharan Africa.

"It was unusual but amazing": demand creation for PrEP among adolescents' men who have sex with men (MSM) and transgender women (TGW) in Brazil

This study aimed to analyze the challenges in demand creation for participation in an HIV pre-exposure prophylaxis (PrEP) project in two Brazilian capitals. This qualitative study was conducted with men who have sex with men and transgender women aged 15 to 19 years who lived in two Brazilian state capitals. For this analysis, 27 semi-structured interviews carried out from 2019 to 2020 were evaluated by reflexive thematic content analysis. For participants, PrEP demand creation was essential for their interaction, mediation, bonding, and attachment and proved effective for PrEP acceptability and adherence. Adolescents' narratives showed that the strategies promoted HIV combination prevention, opened up opportunities for recruitment meetings, helped to negotiate with and convince individuals to use PrEP, strengthened peer education, and evoked a feeling of "being with" and "walking together" despite the challenges. Face-to-face or online interactions using social technologies played a crucial role in recruiting adolescents for the project, expanding knowledge on PrEP and other combination prevention strategies and access to health services and self-care.

Health Economics Research on Non-surgical Biomedical HIV Prevention: Identifying Gaps and Proposing a Way Forward

BACKGROUND AND OBJECTIVE

Although HIV prevention science has advanced over the last four decades, evidence suggests that prevention technologies do not always reach their full potential. Critical health economics evidence at appropriate decision-making junctures, particularly early in the development process, could help identify and address potential barriers to the eventual uptake of future HIV prevention products. This paper aims to identify key evidence gaps and propose health economics research priorities for the field of HIV non-surgical biomedical prevention.

METHODS

We used a mixed-methods approach with three distinct components: (i) three systematic literature reviews (costs and cost effectiveness, HIV transmission modelling and quantitative preference elicitation) to understand health economics evidence and gaps in the peer-reviewed literature; (ii) an online survey with researchers working in this field to capture gaps in yet-to-be published research (recently completed, ongoing and future); and (iii) a stakeholder meeting with key global and national players in HIV prevention, including experts in product development, health economics research and policy uptake, to uncover further gaps, as well as to elicit views on priorities and recommendations based on (i) and (ii).

RESULTS

Gaps in the scope of available health economics evidence were identified. Little research has been carried out on certain key populations (e.g. transgender people and people who inject drugs) and other vulnerable groups (e.g. pregnant people and people who breastfeed). Research is also lacking on preferences of community actors who often influence or enable access to health services among priority populations. Oral pre-exposure prophylaxis, which has been rolled out in many settings, has been studied in depth. However, research on newer promising technologies, such as long-acting pre-exposure prophylaxis formulations, broadly neutralising antibodies and multipurpose prevention technologies, is lacking. Interventions focussing on reducing intravenous and vertical transmission are also understudied. A disproportionate amount of evidence on low- and middle-income countries comes from two countries (South Africa and Kenya); evidence from other countries in sub-Saharan Africa as well as other low- and middle-income countries is needed. Further, data are needed on non-facility-based service delivery modalities, integrated service delivery and ancillary services. Key methodological gaps were also identified. An emphasis on equity and representation of heterogeneous populations was lacking. Research rarely acknowledged the complex and dynamic use of prevention technologies over time. Greater efforts are needed to collect primary data, quantify uncertainty, systematically compare the full range of prevention options available, and validate pilot and modelling data once interventions are scaled up. Clarity on appropriate cost-effectiveness outcome measures and thresholds is also lacking. Lastly, research often fails to reflect policy-relevant questions and approaches.

CONCLUSIONS

Despite a large body of health economics evidence on non-surgical biomedical HIV prevention technologies, important gaps in the scope of evidence and methodology remain. To ensure that high-quality research influences key decision-making junctures and facilitates the delivery of prevention products in a way that maximises impact, we make five broad recommendations related to: improved study design, an increased focus on service delivery, greater community and stakeholder engagement, the fostering of an active network of partners across sectors and an enhanced application of research.

Implementation and resource needs for long-acting PrEP in low- and middle-income countries: a scoping review

INTRODUCTION

Several low- and middle-income countries (LMICs) are preparing to introduce long-acting pre-exposure prophylaxis (LAP). Amid multiple pre-exposure prophylaxis (PrEP) options and constrained funding, decision-makers could benefit from systematic implementation planning and aligned costs. We reviewed national costed implementation plans (CIPs) to describe relevant implementation inputs and activities (domains) for informing the costed rollout of LAP. We assessed how primary costing evidence aligned with those domains.

METHODS

We conducted a rapid review of CIPs for oral PrEP and family planning (FP) to develop a consensus of implementation domains, and a scoping review across nine electronic databases for publications on PrEP costing in LMICs between January 2010 and June 2022. We extracted cost data and assessed alignment with the implementation domains and the Global Health Costing Consortium principles.

RESULTS

We identified 15 implementation domains from four national PrEP plans and FP-CIP template; only six were in all sources. We included 66 full-text manuscripts, 10 reported LAP, 13 (20%) were primary cost studies-representing seven countries, and none of the 13 included LAP. The 13 primary cost studies included PrEP commodities (n = 12), human resources (n = 11), indirect costs (n = 11), other commodities (n = 10), demand creation (n = 9) and counselling (n = 9). Few studies costed integration into non-HIV services (n = 5), above site costs (n = 3), supply chains and logistics (n = 3) or policy and planning (n = 2), and none included the costs of target setting, health information system adaptations or implementation research. Cost units and outcomes were variable (e.g. average per person-year).

DISCUSSION

LAP planning will require updating HIV prevention policies, technical assistance for logistical and clinical support, expanding beyond HIV platforms, setting PrEP achievement targets overall and disaggregated by method, extensive supply chain and logistics planning and support, as well as updating health information systems to monitor multiple PrEP methods with different visit schedules. The 15 implementation domains were variable in reviewed studies. PrEP primary cost and budget data are necessary for new product introduction and should match implementation plans with financing.

CONCLUSIONS

As PrEP services expand to include LAP, decision-makers need a framework, tools and a process to support countries in planning the systematic rollout and costing for LAP.

Infectious Disease Modelling of HIV Prevention Interventions: A Systematic Review and Narrative Synthesis of Compartmental Models

BACKGROUND

The HIV epidemic remains a major public health problem. Critical to transmission control are HIV prevention strategies with new interventions continuing to be developed. Mathematical models are important for understanding the potential impact of these interventions and supporting policy decisions. This systematic review aims to answer the following question: when a new HIV prevention intervention is being considered or designed, what information regarding it is necessary to include in a compartmental model to provide useful insights to policy makers? The primary objective of this review is therefore to assess suitability of current compartmental HIV prevention models for informing policy development.

METHODS

Articles published in EMBASE, Medline, Econlit, and Global Health were screened. Included studies were identified using permutations of (i) HIV, (ii) pre-exposure prophylaxis (PrEP), circumcision (both voluntary male circumcision [VMMC] and early-infant male circumcision [EIMC]), and vaccination, and (iii) modelling. Data extraction focused on study design, model structure, and intervention incorporation into models. Article quality was assessed using the TRACE (TRAnsparent and Comprehensive Ecological modelling documentation) criteria for mathematical models.

RESULTS

Of 837 articles screened, 48 articles were included in the review, with 32 unique mathematical models identified. The substantial majority of studies included PrEP (83%), whilst fewer modelled circumcision (54%), and only a few focussed on vaccination (10%). Data evaluation, implementation verification, and model output corroboration were identified as areas of poorer model quality. Parameters commonly included in the mathematical models were intervention uptake and effectiveness, with additional intervention-specific common parameters identified. We identified key modelling gaps; critically, models insufficiently incorporate multiple interventions acting simultaneously. Additionally, population subgroups were generally poorly represented-with future models requiring improved incorporation of ethnicity and sexual risk group stratification-and many models contained inappropriate data in parameterisation which will affect output accuracy.

CONCLUSIONS

This review identified gaps in compartmental models to date and suggests areas of improvement for models focusing on new prevention interventions. Resolution of such gaps within future models will ensure greater robustness and transparency, and enable more accurate assessment of the impact that new interventions may have, thereby providing more meaningful guidance to policy makers.

Costs and Cost-Effectiveness of Biomedical, Non-Surgical HIV Prevention Interventions: A Systematic Literature Review

BACKGROUND

Considerable evidence on the costs and cost-effectiveness of biomedical, non-surgical interventions to prevent human immunodeficiency virus (HIV) transmission has been generated over the last decade. This study aims to synthesize findings and identify remaining knowledge gaps to suggest future research priorities.

METHODS

A systematic literature review was carried out in August 2020 using the MEDLINE, Embase, Global Health and EconLit databases to retrieve economic evaluations and costing studies of oral pre-exposure prophylaxis (PrEP), injectable long-acting PrEP, vaginal microbicide rings and gels, HIV vaccines and broadly neutralizing antibodies. Studies reporting costs from the provider or societal perspective were included in the analysis. Those reporting on behavioural methods of prevention, condoms and surgical approaches (voluntary medical male circumcision) were excluded. The quality of reporting of the included studies was assessed using published checklists.

RESULTS

We identified 3007 citations, of which 87 studies were retained. Most were set in low- and middle-income countries (LMICs; n = 53) and focused on the costs and/or cost-effectiveness of oral PrEP regimens (n = 70). Model-based economic evaluations were the most frequent study design; only two trial-based cost-effectiveness analyses and nine costing studies were found. Less than half of the studies provided practical details on how the intervention would be delivered by the health system, and only three of these, all in LMICs, explicitly focused on service integration and its implication for delivery costs. 'Real-world' programme delivery mechanisms and costs of intervention delivery were rarely considered. PrEP technologies were generally found to be cost-effective only when targeting high-risk subpopulations. Single-dose HIV vaccines are expected to be cost-effective for all groups despite substantial uncertainty around pricing.

CONCLUSIONS

A lack of primary, detailed and updated cost data, including above-service level costs, from a variety of settings makes it difficult to evaluate the cost-effectiveness of specific delivery modes at scale, or to evaluate strategies for services integration. Closing this evidence gap around real-world implementation is vital, not least because the strategies targeting high-risk groups that are recommended by PrEP models may incur substantially higher costs and be of limited practical feasibility in some settings.

Evaluating the impact of social determinants, conditional cash transfers and primary health care on HIV/AIDS: Study protocol of a retrospective and forecasting approach based on the data integration with a cohort of 100 million Brazilians

Background

Despite the great progress made over the last decades, stronger structural interventions are needed to end the HIV/AIDS pandemic in Low and Middle-Income Countries (LMIC). Brazil is one of the largest and data-richest LMIC, with rapidly changing socioeconomic characteristics and an important HIV/AIDS burden. Over the last two decades Brazil has also implemented the world’s largest Conditional Cash Transfer programs, the Bolsa Familia Program (BFP), and one of the most consolidated Primary Health Care (PHC) interventions, the Family Health Strategy (FHS).

Objective

We will evaluate the effects of socioeconomic determinants, BFP exposure and FHS coverage on HIV/AIDS incidence, treatment adherence, hospitalizations, case fatality, and mortality using unprecedently large aggregate and individual-level longitudinal data. Moreover, we will integrate the retrospective datasets and estimated parameters with comprehensive forecasting models to project HIV/AIDS incidence, prevalence and mortality scenarios up to 2030 according to future socioeconomic conditions and alternative policy implementations.

Methods and analysis

We will combine individual-level data from all national HIV/AIDS registries with large-scale databases, including the “100 Million Brazilian Cohort”, over a 19-year period (2000–2018). Several approaches will be used for the retrospective quasi-experimental impact evaluations, such as Regression Discontinuity Design (RDD), Random Administrative Delays (RAD) and Propensity Score Matching (PSM), combined with multivariable Poisson regressions for cohort analyses. Moreover, we will explore in depth lagged and long-term effects of changes in living conditions and in exposures to BFP and FHS. We will also investigate the effects of the interventions in a wide range of subpopulations. Finally, we will integrate such retrospective analyses with microsimulation, compartmental and agent-based models to forecast future HIV/AIDS scenarios.

Conclusion

The unprecedented datasets, analyzed through state-of-the-art quasi-experimental methods and innovative mathematical models will provide essential evidences to the understanding and control of HIV/AIDS epidemic in LMICs such as Brazil.

Incremental costs of integrated PrEP provision and effective use counselling in community‐based platforms for adolescent girls and young women in South Africa: an observational study

Introduction

Adolescent girls and young women (AGYW) are a priority population for pre‐exposure prophylaxis (PrEP), a highly effective HIV prevention method. However, effective PrEP use among AGYW has been low. Interventions to support PrEP effective use may improve pill‐taking. Affordability of PrEP programs depends on their cost. We, therefore, evaluated the cost of community‐based PrEP with effective use counselling.

Methods

Cost data from a randomized controlled trial were used to evaluate the cost of PrEP provision with effective use counselling offered to AGYW through community‐based HIV testing platforms between November 2018 and November 2019. AGYW were randomized to receive (1) group‐based community health club effective use counselling, (2) individualized effective use counselling or (3) community‐based PrEP dispensary. Task shifting of effective use counselling from nurses to trained lay counsellors was implemented in groups 1 and 2. Personnel costs were estimated from time‐and‐motion observations and staff interviews. Expenditure and ingredients‐based approaches were used to estimate costs for medical and non‐medical supplies.

Results

In total, 603 AGYW initiated PrEP and accrued a total of 1280 months on PrEP. Average cost per person‐month on PrEP with group‐based community health club, individualized effective use counselling and community‐based PrEP dispensary under the Department of Health scenario were similar and high (USD $55.32, $55.65 and $55.46, respectively) due to low PrEP client volume observed in the clinical trial. Increasing client volume (scaled Department of Health scenario) reduced cost per‐person month estimates to USD $15.48, $26.40 and $13.99, respectively.

Conclusions

As designed, individualized effective use counselling increased the cost of standard‐of‐care PrEP delivery by 89%, group‐based community health effective use counselling increased the cost of standard‐of‐care PrEP delivery by 11%. These estimates can inform cost‐effectiveness and budget impact analysis for PrEP provision with effective use counselling services.

Understanding the Evolving Role of Voluntary Medical Male Circumcision as a Public Health Strategy in Eastern and Southern Africa: Opportunities and Challenges

PURPOSE OF REVIEW

Voluntary male medical circumcision (VMMC) has been a cornerstone of HIV prevention in Eastern and Southern Africa (ESA) and is credited in part for declines in HIV incidence seen in recent years. However, these HIV incidence declines change VMMC cost-effectiveness and how it varies across populations.

RECENT FINDINGS

Mathematical models project continued cost-effectiveness of VMMC in much of ESA despite HIV incidence declines. A key data gap is how demand generation cost differs across age groups and over time as VMMC coverage increases. Additionally, VMMC models usually neglect non-HIV effects of VMMC, such as prevention of other sexually transmitted infections and medical adverse events. While small compared to HIV effects in the short term, these could become important as HIV incidence declines. Evidence to date supports prioritizing VMMC in ESA despite falling HIV incidence. Updated modeling methodologies will become necessary if HIV incidence reaches low levels.

The built environment and perceived HIV risk among young women living in the peri-urban slum of Kibra, Nairobi, Kenya

This study reports on the lived experiences of young women living in a peri-urban slum in Kenya and its impact on perceived HIV risk and prevention needs. Guided by the theory of gender and power and postcolonial theory, 73 women 15-24 years of age participated in individual and focus group interviews. Results revealed that the built environment inside and outside the home such as inadequate physical space and lack of security impacted perceived HIV risk. To have meaningful and sustainable change, HIV prevention efforts must address social structures that impact daily lived experiences of young women.

The costs of scaling up HIV and syphilis testing in low- and middle-income countries: a systematic review

Around two-thirds of all new HIV infections and 90% of syphilis cases occur in low- and middle-income countries (LMICs). Testing is a key strategy for the prevention and treatment of HIV and syphilis. Decision-makers in LMICs face considerable uncertainties about the costs of scaling up HIV and syphilis testing. This paper synthesizes economic evidence on the costs of scaling up HIV and syphilis testing interventions in LMICs and evidence on how costs change with the scale of delivery. We systematically searched multiple databases (Medline, Econlit, Embase, EMCARE, CINAHL, Global Health and the NHS Economic Evaluation Database) for peer-reviewed studies examining the costs of scaling up HIV and syphilis testing in LMICs. Thirty-five eligible studies were identified from 4869 unique citations. Most studies were conducted in Sub-Saharan Africa (N = 17) and most explored the costs of rapid HIV in facilities targeted the general population (N = 19). Only two studies focused on syphilis testing. Seventeen studies were cost analyses, 17 were cost-effectiveness analyses and 1 was cost-benefit analysis of HIV or syphilis testing. Most studies took a modelling approach (N = 25) and assumed costs increased linearly with scale. Ten studies examined cost efficiencies associated with scale, most reporting short-run economies of scale. Important drivers of the costs of scaling up included testing uptake and the price of test kits. The 'true' cost of scaling up testing is likely to be masked by the use of short-term decision frameworks, linear unit-cost projections (i.e. multiplying an average cost by a factor reflecting activity at a larger scale) and availability of health system capacity and infrastructure to supervise and support scale up. Cost data need to be routinely collected alongside other monitoring indicators as HIV and syphilis testing continues to be scaled up in LMICs.

Cost of pre-exposure prophylaxis delivery in family planning clinics to prevent HIV acquisition among adolescent girls and young women in Kisumu, Kenya

INTRODUCTION

Oral pre-exposure prophylaxis (PrEP) is increasingly being implemented in sub-Saharan Africa. Adolescent girls and young women (AGYW) in Kenya contribute more than half of all new infections among young people aged 15-24 years, highlighting the need for evidence on the cost of PrEP in real-world implementation to inform the budget impact, cost-effectiveness, and financial sustainability of PrEP programs.

METHODS

We estimated the cost of delivering PrEP to AGYW enrolled in a PrEP implementation study in two family planning clinics in Kisumu county, located in western Kenya. We derived total annual costs and the average cost per client-month of PrEP by input type (variable or fixed) and visit type (initiation or follow-up). We estimated all costs as implemented in the study, and under implementation by the Kenyan Ministry of Health (MoH), both at the program volume observed and if the facilities were delivering PrEP at full capacity (scaled-MoH).

RESULTS

For the costing period between March 2018 and March 2019, 615 HIV-negative women contributed 1,128 (502 initiation and 626 follow-up) visits. The average cost per client-month of PrEP dispensed per study protocol and per the MoH scenario was $28.92 and $14.52, respectively. If the MoH scaled the program so that facilities could see PrEP clients at capacity, the average cost per client-month of PrEP was $10.88. Medication costs accounted for the largest proportion of the total annual costs (48% in MoH scenario and 65% in the scaled-MoH scenario).

CONCLUSIONS

Using data from a PrEP implementation program, we found that the cost per client-month of PrEP dispensed is reduced by 62% if PrEP delivery at the two clinics is scaled up by the MoH. Our findings are valuable for informing local resource allocation and budgetary cost projections for scale-up of PrEP delivery to AGYW. Additionally, previous cost-effectiveness studies have been limited by the use of fixed assumptions of the cost of PrEP per person-month. Our study provides cost estimates from practical data which will better inform cost-effectiveness and budget impact analyses.

Large benefits to youth-focused HIV treatment-as-prevention efforts in generalized heterosexual populations: An agent-based simulation model

Predominantly heterosexual HIV-1 epidemics like those in sub-Saharan Africa continue to have high HIV incidence in young people. We used a stochastic, agent-based model for age-disparate networks to test the hypothesis that focusing uptake and retention of ART among youth could enhance the efficiency of treatment as prevention (TasP) campaigns. We used the model to identify strategies that reduce incidence to negligible levels (i.e., < 0.1 cases/100 person-years) 20-25 years after initiation of a targeted TasP campaign. The model was parameterized using behavioral, demographic, and clinical data from published papers and national reports. To keep a focus on the underlying age effects we model a generalized heterosexual population with average risks (i.e., no MSM, no PWIDs, no sex workers) and no entry of HIV+ people from other regions. The model assumes that most people (default 95%, range in variant simulations 60-95%) are "linkable"; i.e., could get linked to effective care given sufficient resources. To simplify the accounting, we assume a rapid jump in the number of people receiving treatment at the start of the TasP campaign, followed by a 2% annual increase that continues until all linkable HIV+ people have been treated. Under historical scenarios of CD4-based targeted ART allocation and current policies of untargeted (random) ART allocation, our model predicts that viral replication would need to be suppressed in 60-85% of infected people at the start of the TasP campaign to drive incidence to negligible levels. Under age-based strategies, by contrast, this percentage dropped by 18-54%, depending on the strength of the epidemic and the age target. For our baseline model, targeting those under age 30 halved the number of people who need to be treated. Age-based targeting also minimized total and time-discounted AIDS deaths over 25 years. Age-based targeting yielded benefits without being highly exclusive; in a model in which 60% of infected people were treated, ~87% and ~58% of those initiating therapy during a campaign targeting those <25 and <30 years, respectively, fell outside the target group. Sensitivity analyses revealed that youth-focused TasP is beneficial due to age-related risk factors (e.g. shorter relationship durations), and an age-specific herd immunity (ASHI) effect that protects uninfected adolescents entering the sexually active population. As testing rates increase in response to UNAIDS 90-90-90 goals, efforts to link all young people to care and treatment could contribute enormously to ending the HIV epidemic.

The impact, cost and cost-effectiveness of oral pre-exposure prophylaxis in sub-Saharan Africa: a scoping review of modelling contributions and way forward

INTRODUCTION

Oral pre-exposure prophylaxis (PrEP) is a new form of HIV prevention being considered for inclusion in national prevention portfolios. Many mathematical modelling studies have been undertaken that speak to the impact, cost and cost-effectiveness of PrEP programmes. We assess the available evidence from mathematical modelling studies to inform programme planning and policy decision making for PrEP and further research directions.

METHODS

We conducted a scoping review of the published modelling literature. Articles published in English which modelled oral PrEP in sub-Saharan Africa, or non-specific settings with relevance to generalized HIV epidemic settings, were included. Data were extracted for the strategies of PrEP use modelled, and the impact, cost and cost-effectiveness of PrEP for each strategy. We define an algorithm to assess the quality and relevance of studies included, summarize the available evidence and identify the current gaps in modelling. Recommendations are generated for future modelling applications and data collection.

RESULTS AND DISCUSSION

We reviewed 1924 abstracts and included 44 studies spanning 2007 to 2017. Modelling has reported that PrEP can be a cost-effective addition to HIV prevention portfolios for some use cases, but also that it would not be cost-effective to fund PrEP before other prevention interventions are expanded. However, our assessment of the quality of the modelling indicates cost-effectiveness analyses failed to comply with standards of reporting for economic evaluations and the assessment of relevance highlighted that both key parameters and scenarios are now outdated. Current evidence gaps include modelling to inform service development using updated programmatic information and ex post modelling to evaluate and inform efficient deployment of resources in support of PrEP, especially among key populations, using direct evidence of cost, adherence and uptake patterns.

CONCLUSIONS

Updated modelling which more appropriately captures PrEP programme delivery, uses current intervention scenarios, and is parameterized with data from demonstration and implementation projects is needed in support of more conclusive findings and actionable recommendations for programmes and policy. Future analyses should address these issues, aligning with countries to support the needs of programme planners and decision makers for models to more directly inform programme planning and policy.

Mathematical modelling to inform 'treat all' implementation in sub-Saharan Africa: a scoping review

OBJECTIVE

Despite widespread uptake, only half of sub-Saharan African countries have fully implemented the World Health Organization's 'treat all' policy, hindering achievement of global HIV targets. We examined literature on mathematical modelling studies that sought to inform scale-up and implementation of 'treat all' in sub-Saharan Africa.

METHODS

We conducted a scoping review, a research synthesis to assess emerging evidence and identify gaps, of peer-reviewed literature, extracting study characteristics on 'treat all' policies and assumptions, setting, key populations, outcomes and findings. Studies were narratively summarised and potential gaps characterised.

RESULTS

We identified 16 studies examining 'treat all' alone (n=12) or with expanded testing (n=7) and/or care continuum improvements (n=6). Twelve studies examined 'treat all' for Southern African countries, while none did so for Central Africa. Four included the role of resistance; one evaluated any key population. A range of health and economic outcomes were reported, although fewer studies formally assessed budget impact. Fourteen studies involved co-authors with any in-country affiliation; one study also had co-authors with local government affiliation. Overall, 'treat all' improves health outcomes and is cost-effective compared to deferred HIV treatment; 'treat all' with expanded testing or care continuum improvements may provide further health benefits. However, studies generally used optimistic assumptions about the implementation of expanded testing or care continuum improvements.

CONCLUSIONS

The modelling literature demonstrates improved health and economic benefits of 'treat all'. Using mathematical modelling to inform real-world implementation of 'treat all' requires realistic assumptions about expanded testing and care continuum interventions across a wide range of settings and populations.

Lessons from a decade of voluntary medical male circumcision implementation and their application to HIV pre-exposure prophylaxis scale up

Oral pre-exposure prophylaxis (PrEP) has the ability to curb HIV incidence worldwide and bring us closer to ending the HIV epidemic. Scale up of PrEP service delivery has many similar challenges to those faced by voluntary medical male circumcision (VMMC) services roll-out. This article outlines ten important lessons learned during the scale up of VMMC services in sub-Saharan Africa and their application to current oral PrEP implementation efforts to promote faster expansion for public health impact.

The influence of mobility among high-risk populations on HIV transmission in Western Kenya

Western Kenya suffers a highly endemic and also very heterogeneous epidemic of human immunodeficiency virus (HIV). Although female sex workers (FSW) and their male clients are known to be at high risk for HIV, HIV prevalence across regions in Western Kenya is not strongly correlated with the fraction of women engaged in commercial sex. An agent-based network model of HIV transmission, geographically stratified at the county level, was fit to the HIV epidemic, scale-up of interventions, and populations of FSW in Western Kenya under two assumptions about the potential mobility of FSW clients. In the first, all clients were assumed to be resident in the same geographies as their interactions with FSW. In the second, some clients were considered non-resident and engaged only in interactions with FSW, but not in longer-term non-FSW partnerships in these geographies. Under both assumptions, the model successfully reconciled disparate geographic patterns of FSW and HIV prevalence. Transmission patterns in the model suggest a greater role for FSW in local transmission when clients were resident to the counties, with 30.0% of local HIV transmissions attributable to current and former FSW and clients, compared to 21.9% when mobility of clients was included. Nonetheless, the overall epidemic drivers remained similar, with risky behavior in the general population dominating transmission in high-prevalence counties. Our modeling suggests that co-location of high-risk populations and generalized epidemics can further amplify the spread of HIV, but that large numbers of formal FSW and clients are not required to observe or mechanistically explain high HIV prevalence in the general population.