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Objectives Although the efficacy of traditional 3-drug regimens for the treatment of HIV is well established, tolerability and toxicity concerns remain. New 2-drug regimens such as Juluca (dolutegravir [DTG]/rilpivirine [RPV]) offer noninferior efficacy versus 3-drug regimens (SWORD-1 and SWORD-2 studies), while reducing cumulative drug exposure and potentially long-term toxicities and drug-drug interactions. Here, we assess the cost-effectiveness of DTG/RPV for the treatment of HIV-1 for virologically suppressed adults in Taiwan. Methods A hybrid decision tree and Markov cohort state transition model was used to evaluate the expected economic costs and clinical outcomes associated with DTG/RPV and comparators. Model health states were defined by viral load and CD4 cell count. Efficacy and safety data were informed from SWORD-1 and SWORD-2 studies and the literature. The risk of long-term toxicities (cardiovascular disease, bone fractures, and chronic kidney disease) were included. Current branded drug acquisition prices were included, and healthcare costs informed by a bespoke costing study using National Health Insurance Research Database data. Incremental cost-effectiveness ratios were calculated and compared with a willingness-to-pay threshold of 2 times Taiwan’s gross domestic product (NT$1 550 000). Results DTG/RPV was found to be a cost-saving regimen compared to 3 comparators (rilpivirine [RPV]/emtricitabine [FTC]/tenofovir disoproxil fumarate [TDF], dolutegravir [DTG]/abacavir [ABC]/lamivudine [3TC], and elvitegravir [EVG]/cobicistat [c]/emtricitabine [FTC]/tenofovir alafenamide [TAF]) and fell in the southwest quadrant of the cost-effectiveness plane where it is generating significant savings with a small decrement in lifetime quality-adjusted life-years (–0.005). It was, however, more expensive than efavirenz [EFV]/emtricitabine [FTC]/ tenofovir disoproxil fumarate [TDF]. Conclusions DTG/RPV is cost-saving compared to RPV/FTC/TDF, DTG/ABC/3TC, and EVG/c/FTC/TAF, and provides comparable efficacy with reduced cumulative drug exposure.

Heavily treatment-experienced (HTE) people with multidrug-resistant HIV-1 have limited treatment options. Treatment with the first-in-class attachment inhibitor fostemsavir in addition to optimized background therapy (OBT) resulted in sustained virologic and immunologic responses in HTE participants throughout 96 weeks in the BRIGHTE trial. In the absence of long-term direct comparative evidence between fostemsavir-based and other antiretroviral regimens, this analysis indirectly compares efficacy and safety across relevant available trials, adjusting for demographic and baseline characteristics.A systematic literature review was conducted to identify trials with designs and populations comparable to BRIGHTE. Using matching-adjusted indirect comparison analyses, individual participant data from BRIGHTE were reweighted to create balanced populations across trials, and efficacy and safety outcomes were compared.Three comparator trials were identified, 2 of which reflected an optimized therapy without fostemsavir (OBT alone): TMB-301 (ibalizumab and OBT), BENCHMRK-1/-2 (OBT alone), and VIKING-3 (OBT alone). Compared with ibalizumab and OBT (N = 40), fostemsavir and OBT (unadjusted, N = 347; adjusted, N = 236) were associated with numerically higher nonsignificant odds of virologic suppression (odds ratio [OR] = 1.44; 95% CI, 0.74-2.80; P = 0.284) and a similar increase in CD4Although matching-adjusted indirect comparison analyses have limitations, these results support the use of fostemsavir and OBT as an important treatment option in HTE people with multidrug-resistant HIV-1.

BACKGROUND: Dolutegravir(DTG)/lamivudine(3TC) is the first 2-drug regimen recommended as an initial treatment for people living with HIV (PLHIV). OBJECTIVE: To assess the cost-effectiveness and potential budget impact of DTG/3TC in the US healthcare setting. METHODS: A previously published hybrid decision-tree and Markov cohort state transition model was adapted to estimate the incremental costs and health outcome benefits over a patients' lifetime. DTG/3TC was compared with current standard of care in treatment naive and treatment experienced virologically suppressed PLHIV. Health states included in the model were based upon virologic response and CD4 cell count, with death as an absorbing state. Clinical data was informed by the Phase III GEMINI 1 and 2 clinical trials, a published network meta-analysis (NMA) in treatment-naive patients and the Phase III TANGO clinical trial in treatment experienced patients. Costs and utilities were informed by published data and discounted annually at a rate of 3%. A separate 5-year budget impact analysis was conducted assuming 5%-15% uptake in eligible treatment naive and 10%-30% uptake in eligible treatment experienced patients. RESULTS: In the treatment naive analyses based on GEMINI 1 and 2, DTG/3TC dominated, i.e., was less costly and more effective, than all comparators. DTG/3TC resulted in 0.083 incremental quality-adjusted life-years (QALYs) at a cost saving of $199,166 compared with the DTG + tenofovir disoproxil(TDF)/emtricitabine(FTC) comparator arm. The incremental QALY and cost savings for DTG/3TC compared with DTG/abacavir(ABC)/3TC, cobicistat-boosted darunavir(DRV/c)/tenofovir alafenamide(TAF)/FTC, and bictegravir (BIC)/TAF/FTC, based on NMA results were 0.465, 0.142, and 0.698, and $42,948, $122,846, and $44,962, respectively. In the analyses of treatment-experienced virologically suppressed patients based on TANGO, DTG/3TC offered slightly lower QALYs (-0.037) with an estimated savings of $78,730 when compared with continuation of TAF-based regimen (TBR). Sensitivity analyses demonstrated that these conclusions were relatively insensitive to alternative parameter estimates. The budget impact analysis estimated that by 5th year a total of 70,240 treatment naive patients and 1,340,480 treatment experienced patients could be eligible to be prescribed DTG/3TC. The estimated budget savings over 5 years ranged from $1.12b to $3.35b (corresponding to 27,512 to 82,536 on DTG/3TC by year 5) in the lowest and highest uptake scenarios, respectively. CONCLUSION: In conclusion, DTG/3TC with its comparable efficacy and lower drug acquisition costs, has the potential to offer significant cost savings to US healthcare payers for the initial treatment of treatment naive patients and as a treatment switching option for virologically suppressed patients. DISCLOSURES: This study was funded in full by ViiV healthcare, Brentford, UK. Medical writing to support this study was also funded in full by ViiV Healthcare, Brentford, UK. Butler, Hayward, and Jacob are employees of HEOR Ltd, the company performing this study funded by ViiV Healthcare. Anderson is an employee of GlaxoSmithKline and owns shares in the company. Punekar, Evitt, and Oglesby are employees of ViiV Healthcare and own stocks in GlaxoSmithKline.

Introduction Heavily treatment-experienced (HTE) people living with HIV-1 (PLWH) have limited viable antiretroviral regimens available because of multidrug resistance and safety concerns. The first-in-class HIV-1 attachment inhibitor fostemsavir demonstrated efficacy and safety in HTE participants in the ongoing phase III BRIGHTE trial. Objectives We describe patient-reported outcomes (PROs) through week 48. Methods Eligible participants for whom their current regimen was failing were assigned to the randomized cohort (RC; one to two fully active agents remaining) or the nonrandomized cohort (NRC; no fully active agents remaining). PRO assessments included the EQ-5D-3L, EQ-VAS, and Functional Assessment of HIV Infection (FAHI) instruments. Results Both cohorts achieved increases in EQ-5D-3L US- and UK-referenced utility score from baseline at week 24. Mean visual analog scale (VAS) scores in the RC and NRC increased from baseline by 8.7 (95% CI 6.2–11.2) and 5.6 points (95% CI 1.5–9.7) at week 24 and increased from baseline by 9.8 (95% CI 7.0–12.6) and 4.9 points (95% CI 0.6–9.2) at week 48, respectively. Mean increases in FAHI total score from baseline to weeks 24 and 48 in the RC were 6.9 (95% CI 4.2–9.7) and 5.8 (95% CI 2.7–9.0), respectively, whereas mean increases in physical and emotional well-being subscale scores were 2.7 (95% CI 1.9–3.6) and 2.4 (95% CI 1.3–3.4) and 3.2 (95% CI 2.2–4.2) and 2.6 (95% CI 1.6–3.7), respectively, with little to no change in other subscales. Conclusions Improvements in major domains of the EQ-VAS and FAHI through week 48, combined with efficacy and safety results, support the use of fostemsavir for HTE PLWH. Trial Registration Number and Date NCT02362503; February 13, 2015.

As life expectancy of patients infected with human immunodeficiency virus (HIV) approaches that of the general population, the composition of HIV management costs is likely to change.To (a) review treatment and disease management costs in HIV, including costs of adverse events (AEs) related to antiretroviral therapy (ART) and long-term toxicities, and (b) explore the evolving cost drivers.A targeted literature review between January 2012 and November 2017 was conducted using PubMed and major conferences. Articles reporting U.S. costs of HIV management, acquired immunodeficiency syndrome (AIDS)-defining events, end of life care, and ART-associated comorbidities such as cardiovascular disease (CVD), chronic kidney disease (CKD), and osteoporosis were included. All costs were inflated to 2017 U.S. dollars. A Markov model-based analysis was conducted to estimate the effect of increased life expectancy on costs associated with HIV treatment and management.22 studies describing HIV costs in the United States were identified, comprising 16 cost-effectiveness analysis studies, 5 retrospective analyses of health care utilization, and 1 cost analysis in a resource-limited setting. Management costs per patient per month, including routine care costs (on/off ART), non-HIV medication, opportunistic infection prophylaxis, inpatient utilization, outpatient utilization, and emergency department utilization were reported as CD4+ cell-based health state costs ranging from $1,192 for patients with CD4500 cells/mmThis study identified and summarized holistic cost estimates appropriate for use within U.S. HIV cost-effectiveness analyses and demonstrates an increasing contribution of comorbidity outcomes, primarily associated with aging in addition to long-term treatment with ART, not typically evaluated in contemporary HIV cost-effectiveness analyses.This analysis was sponsored by ViiV Healthcare, which had no role in the analyses and interpretation of study results. Ward, Sugrue, Hayward, and McEwan are employees of HEOR Ltd, which received funding from ViiV Healthcare to conduct this study. Anderson is an employee of GlaxoSmithKline and holds shares in the company. Punekar and Oglesby are employees of ViiV Healthcare and hold shares in GlaxoSmithKline. Lopes was employed by ViiV Healthcare at the time of the study and holds shares in GlaxoSmithKline.

Although the efficacy of traditional 3-drug regimens for the treatment of HIV is well established, tolerability and toxicity concerns remain. New 2-drug regimens such as Juluca (dolutegravir [DTG]/rilpivirine [RPV]) offer noninferior efficacy versus 3-drug regimens (SWORD-1 and SWORD-2 studies), while reducing cumulative drug exposure and potentially long-term toxicities and drug-drug interactions. Here, we assess the cost-effectiveness of DTG/RPV for the treatment of HIV-1 for virologically suppressed adults in Taiwan.A hybrid decision tree and Markov cohort state transition model was used to evaluate the expected economic costs and clinical outcomes associated with DTG/RPV and comparators. Model health states were defined by viral load and CD4 cell count. Efficacy and safety data were informed from SWORD-1 and SWORD-2 studies and the literature. The risk of long-term toxicities (cardiovascular disease, bone fractures, and chronic kidney disease) were included. Current branded drug acquisition prices were included, and healthcare costs informed by a bespoke costing study using National Health Insurance Research Database data. Incremental cost-effectiveness ratios were calculated and compared with a willingness-to-pay threshold of 2 times Taiwan's gross domestic product (NT$1 550 000).DTG/RPV was found to be a cost-saving regimen compared to 3 comparators (rilpivirine [RPV]/emtricitabine [FTC]/tenofovir disoproxil fumarate [TDF], dolutegravir [DTG]/abacavir [ABC]/lamivudine [3TC], and elvitegravir [EVG]/cobicistat [c]/emtricitabine [FTC]/tenofovir alafenamide [TAF]) and fell in the southwest quadrant of the cost-effectiveness plane where it is generating significant savings with a small decrement in lifetime quality-adjusted life-years (-0.005). It was, however, more expensive than efavirenz [EFV]/emtricitabine [FTC]/ tenofovir disoproxil fumarate [TDF].DTG/RPV is cost-saving compared to RPV/FTC/TDF, DTG/ABC/3TC, and EVG/c/FTC/TAF, and provides comparable efficacy with reduced cumulative drug exposure.

Background Current antiretroviral therapy (ART) has dramatically improved outcomes for people living with HIV (PLWHIV), however adherence to daily oral dosing remains a challenge for some. New, long-acting (LA) ARTs which are directly administered by physicians eliminate the need to adhere to daily oral dosing and may improve clinical outcomes. The study objective was to evaluate costs and QALYs associated with improved adherence achieved via a novel, directly-observed therapy (DOT) of a monthly LA injectable ART, compared to standard of care (SoC), daily oral therapy. Methods A published Markov cohort state-transition model was adapted to model the impact of treatment adherence and subsequent disease transmission. Without the need to adhere to daily dosing, the efficacy of the injectable was modelled independent of adherence whereas virologic suppression in the SoC arm was adjusted to reflect published data on adherence to daily dosing (8.12% below optimal levels observed in clinical trials). Results This evidence-based approach of accounting for adherence revealed an increase in lifetime costs for oral SOC of approximately $850, and QALY loss of 0.109 when compared to results without accounting for adherence. Disease transmission results yielded 3 cases averted of HIV per 1,000 patients with LA’s impact on adherence. Conclusion In the absence of comparative adherence estimates between a LA, injectable DOT and daily oral therapy in the real world, an evidence-based approach provides a method to address the uncertainty around the true impact on costs and QALYs of a novel mode of administration. Disclosures Erin Arthurs, MSc, GlaxoSmithKline (Employee) Ben Parker, MSc, HEOR Ltd. (Employee) Ian Jacob, MSc, HEOR Ltd (Employee) Debbie Becker, MSc, GSK (Consultant) Amy Lee, MSc, PhD, GSK (Consultant) Olivia Hayward, PhD, HEOR ltd. (Employee) Vasiliki Chounta, MSc, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Sarah-Jane Anderson, PhD, GlaxoSmithKline (Employee, Shareholder) Nicolas Van de Velde, PhD, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee)

Summary Background Advances in HIV prevention methods offer promise to accelerate declines in incidence, but how these methods can be deployed to have the best effect on the heterogeneous landscape and drivers of the pandemic remains unclear. We postulated that use of epidemic heterogeneity to inform the allocation of resources for combination HIV prevention could enhance the impact of HIV funding across sub-Saharan Africa. Methods We developed a compartmental mathematical model of HIV transmission and disease progression by risk group to subnational resolution in 18 countries, capturing 80% of the adult HIV burden in sub-Saharan Africa. Adults aged 15–49 years were grouped by risk of HIV acquisition and transmission, and those older than 50 years were assumed to have negligible risk. For each top-level administrative division, we calibrated the model to historical data for HIV prevalence, sexual behaviours, treatment scale-up, and demographics. We then evaluated four strategies for allocation of prevention funding over a 15 year period from 2016 to 2030, which exploited epidemic differences between subnational regions to varying degrees. Findings For a $US20 billion representative expenditure over the 15 year period, scale-up of prevention along present funding channels could avert 5·3 million infections relative to no scale-up. Prioritisation of key populations could avert 3·7 million more infections than present funding channels, and additional prioritisation by within-country geography could avert 400 000 more infections. Removal of national constraints could avert a further 600 000 infections. Risk prioritisation has greater marginal impact than geographical prioritisation across multiple expenditure levels. However, targeting by both risk and geography is best for total impact and could achieve gains of up to three times more than present channels. A shift from the present pattern to the optimum pattern would rebalance resources towards more cost-effective interventions and emerging epidemics. Interpretation If domestic and international funders were to align strategically to build an aggregate funding pattern that is guided by the epidemiology of HIV, and particularly by the emerging understanding of local dynamics and epidemic drivers, more cost-effective and impactful HIV prevention investments could be achieved across sub-Saharan Africa. Funding The Bill & Melinda Gates Foundation.

Introduction Setting and monitoring progress towards targets for HIV control is critical in ensuring responsive programmes. Here, we explore how to apply targets for reduction in HIV incidence to local settings and which indicators give the strongest signal of a change in incidence in the population and are therefore most important to monitor. Methods We use location‐specific HIV transmission models, tailored to the epidemics in the counties and major cities in Kenya, to project a wide range of plausible future epidemic trajectories through varying behaviours, treatment coverage and prevention interventions. We look at the change in incidence across modelled scenarios in each location between 2015 and 2030 to inform local target setting. We also simulate the measurement of a library of potential indicators and assess which are most strongly associated with a change in incidence. Results Considerable variation was observed in the trajectory of the local epidemics under the plausible scenarios defined (only 10 of 48 locations saw a median reduction in incidence of greater than or equal to an 80% target by 2030). Indicators that provide strong signals in certain epidemic types may not perform consistently well in settings with different epidemiological features. Predicting changes in incidence is more challenging in advanced generalized epidemics compared to concentrated epidemics where changes in high‐risk sub‐populations track more closely to the population as a whole. Many indicators demonstrate only limited association with incidence (such as “condom use” or “pre‐exposure prophylaxis coverage”). This is because many other factors (low effectiveness, impact of other interventions, countervailing changes in risk behaviours, etc.) can confound the relationship between interventions and their ultimate long‐term impact, especially for an intervention with low expected coverage. The population prevalence of viral suppression shows the most consistent associations with long‐term changes in incidence even in the largest generalized epidemics. Conclusions Target setting should be appropriate for the local epidemic and what can feasibly be achieved. There is no one universally reliable indicator to predict future HIV incidence across settings. Thus, the signature of epidemic control must contain indications of success across a wide range of interventions and outcomes.

Introduction Due to the nature of funding, national planners and international donors typically balance budgets over short time periods when designing HIV programmes (˜5‐year funding cycles). We aim to explicitly quantify the cost of short‐term funding arrangements on the success of future HIV prevention programmes. Methods Using mathematical models of HIV transmission in Kenya, we compare the impact of optimized combination prevention strategies under different constraints on investment over time. Each scenario has the same total budget for the 30‐year intervention period but the pattern of spending over time is allowed to vary. We look at the impact of programmes with decreasing, increasing or constant spending across 5‐year funding cycles for a 30‐year period. Interventions are optimized within each funding cycle such that strategies take a short‐term view of the epidemic. We compare these with two strategies with no spending pattern constraints: one with static intervention choices and another flexible strategy with interventions changed in year ten. Results and Discussion For the same total 30‐year budget, greatest impact is achieved if larger initial prevention spending is offset by later treatment savings which leads to accumulating benefits in reduced infections. The impact under funding cycle constraints is determined by the extent to which greater initial spending is permitted. Short‐term funding constraints and funds held back to later years may reduce impact by up to 18% relative to the flexible long‐term strategy. Conclusions Ensuring that funding arrangements are in place to support long‐term prevention strategies will make spending most impactful. Greater prevention spending now will bring considerable returns through reductions in new infections, greater population health and reductions in the burden on health services in the future.

Introduction A strategic approach to the application of HIV prevention interventions is a core component of the UNAIDS Fast Track strategy to end the HIV epidemic by 2030. Central to these plans is a focus on high‐prevalence geographies, in a bid to target resources to those in greatest need and maximize the reduction in new infections. Whilst this idea of geographical prioritization has the potential to improve efficiency, it is unclear how it should be implemented in practice. There are a range of prevention interventions which can be applied differentially across risk groups and locations, making allocation decisions complex. Here, we use mathematical modelling to compare the impact (infections averted) of a number of different approaches to the implementation of geographical prioritization of prevention interventions, similar to those emerging in policy and practice, across a range of prevention budgets. Methods We use geographically specific mathematical models of the epidemic and response in 48 counties and major cities of Kenya to project the impact of the different geographical prioritization approaches. We compare the geographical allocation strategies with a nationally uniform approach under which the same interventions must be applied across all modelled locations. Results We find that the most extreme geographical prioritization strategy, which focuses resources exclusively to high‐prevalence locations, may substantially restrict impact (41% fewer infections averted) compared to a nationally uniform approach, as opportunities for highly effective interventions for high‐risk populations in lower‐prevalence areas are missed. Other geographical allocation approaches, which intensify efforts in higher‐prevalence areas whilst maintaining a minimum package of cost‐effective interventions everywhere, consistently improve impact at all budget levels. Such strategies balance the need for greater investment in locations with the largest epidemics whilst ensuring higher‐risk groups in lower‐priority locations are provided with cost‐effective interventions. Conclusions Our findings serve as a warning to not be too selective in the application of prevention strategies. Further research is needed to understand how decision‐makers can find the right balance between the choice of interventions, focus on high‐risk populations, and geographical targeting to ensure the greatest impact of HIV prevention.

Summary Background Epidemiological data show substantial variation in the risk of HIV infection between communities within African countries. We hypothesised that focusing appropriate interventions on geographies and key populations at high risk of HIV infection could improve the effect of investments in the HIV response. Methods With use of Kenya as a case study, we developed a mathematical model that described the spatiotemporal evolution of the HIV epidemic and that incorporated the demographic, behavioural, and programmatic differences across subnational units. Modelled interventions (male circumcision, behaviour change communication, early antiretoviral therapy, and pre-exposure prophylaxis) could be provided to different population groups according to their risk behaviours or their location. For a given national budget, we compared the effect of a uniform intervention strategy, in which the same complement of interventions is provided across the country, with a focused strategy that tailors the set of interventions and amount of resources allocated to the local epidemiological conditions. Findings A uniformly distributed combination of HIV prevention interventions could reduce the total number of new HIV infections by 40% during a 15-year period. With no additional spending, this effect could be increased by 14% during the 15 years—almost 100 000 extra infections, and result in 33% fewer new HIV infections occurring every year by the end of the period if the focused approach is used to tailor resource allocation to reflect patterns in local epidemiology. The cumulative difference in new infections during the 15-year projection period depends on total budget and costs of interventions, and could be as great as 150 000 (a cumulative difference as great as 22%) under different assumptions about the unit costs of intervention. Interpretation The focused approach achieves greater effect than the uniform approach despite exactly the same investment. Through prioritisation of the people and locations at greatest risk of infection, and adaption of the interventions to reflect the local epidemiological context, the focused approach could substantially increase the efficiency and effectiveness of investments in HIV prevention. Funding The Bill & Melinda Gates Foundation and UNAIDS.

Transmission dynamic models linked to economic analyses often form part of the decision making process when introducing new chlamydia screening interventions. Outputs from these transmission dynamic models can vary depending on the values of the parameters used to describe the infection. Therefore these values can have an important influence on policy and resource allocation. The risk of progression from infection to pelvic inflammatory disease has been extensively studied but the parameters which govern the transmission dynamics are frequently neglected. We conducted a systematic review of transmission dynamic models linked to economic analyses of chlamydia screening interventions to critically assess the source and variability of the proportion of infections that are asymptomatic, the duration of infection and the transmission probability. We identified nine relevant studies in Pubmed, Embase and the Cochrane database. We found that there is a wide variation in their natural history parameters, including an absolute difference in the proportion of asymptomatic infections of 25% in women and 75% in men, a six-fold difference in the duration of asymptomatic infection and a four-fold difference in the per act transmission probability. We consider that much of this variation can be explained by a lack of consensus in the literature. We found that a significant proportion of parameter values were referenced back to the early chlamydia literature, before the introduction of nucleic acid modes of diagnosis and the widespread testing of asymptomatic individuals. In conclusion, authors should use high quality contemporary evidence to inform their parameter values, clearly document their assumptions and make appropriate use of sensitivity analysis. This will help to make models more transparent and increase their utility to policy makers.

Background The decision to implement a Chlamydia screening programme is based on a detailed assessment of its projected impact and cost-effectiveness. In the absence of evidence from randomised controlled trials, transmission dynamic models are crucial to this process. However these models are highly sensitive to the representation of the infection. We review the evidence used to inform the model parameters highlighting their strengths and limitations. Methods Published economic analyses of chlamydia screening interventions were identified following a systematic search of the literature. Only transmission dynamic models were included as they represent the gold standard. Parameters describing chlamydia infection were extracted and the variability across the studies assessed. The data used to inform each parameter was sourced and critically evaluated. Results Eleven studies were included in this review, all evaluating chlamydia screening programme designs in developed countries. Many key natural history parameters are based on sparse historical data and there is wide variation in the values used across the models. For example, The per act transmission probability ranging from 3.75% to 15.3%. The modelled duration of asymptomatic infection was between 180–370 days in women and 40–200 days in men. Only one paper includes a period of protective immunity following infection. Only 2 studies consider the role of reinfection in the development of complications However, there is a general consensus in the proportion of people that are asymptomatic; between 70–75% of women and 25–50% of men. Conclusion We highlight the variability in descriptions of the natural history and emphasise the importance of using contemporary data to inform modelling studies. A clear consensus on the appropriate representation of the natural history is needed, with estimates continuously updated using new evidence.

Summary Background Many ways of preventing HIV infection have been proposed and more are being developed. We sought to construct a strategic approach to HIV prevention that would use limited resources to achieve the greatest possible prevention impact through the use of interventions available today and in the coming years. Methods We developed a deterministic compartmental model of heterosexual HIV transmission in South Africa and formed assumptions about the costs and effects of a range of interventions, encompassing the further scale-up of existing interventions (promoting condom use, male circumcision, early antiretroviral therapy [ART] initiation for all [including increased HIV testing and counselling activities], and oral pre-exposure prophylaxis [PrEP]), the introduction of new interventions in the medium term (offering intravaginal rings, long-acting injectable antiretroviral drugs) and long term (vaccine, broadly neutralising antibodies [bNAbs]). We examined how available resources could be allocated across these interventions to achieve maximum impact, and assessed how this would be affected by the failure of the interventions to be developed or scaled up. Findings If all interventions are available, the optimum mix would place great emphasis on the following: scale-up of male circumcision and early ART initiation with outreach testing, as these are available immediately and assumed to be low cost and highly efficacious; intravaginal rings targeted to sex workers; and vaccines, as these can achieve a large effect if scaled up even if imperfectly efficacious. The optimum mix would rely less on longer term developments, such as long-acting antiretroviral drugs and bNAbs, unless the costs of these reduced. However, if impossible to scale up existing interventions to the extent assumed, emphasis on oral PrEP, intravaginal rings, and long-acting antiretroviral drugs would increase. The long-term effect on the epidemic is most affected by scale-up of existing interventions and the successful development of a vaccine. Interpretation With current information, a strategic approach in which limited resources are used to maximise prevention impact would focus on strengthening the scale-up of existing interventions, while pursuing a workable vaccine and developing other approaches that can be used if further scale-up of existing interventions is limited. Funding Bill & Melinda Gates Foundation.