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BackgroundApproaches that allow easy access to pre-exposure prophylaxis (PrEP), such as over-the-counter provision at pharmacies, could facilitate risk-informed PrEP use and lead to lower HIV incidence, but their cost-effectiveness is unknown. We aimed to evaluate conditions under which risk-informed PrEP use is cost-effective.MethodsWe applied a mathematical model of HIV transmission to simulate 3000 setting-scenarios reflecting a range of epidemiological characteristics of communities in sub-Saharan Africa. The prevalence of HIV viral load greater than 1000 copies per mL among all adults (HIV positive and negative) varied from 1·1% to 7·4% (90% range). We hypothesised that if PrEP was made easily available without restriction and with education regarding its use, women and men would use PrEP, with sufficient daily adherence, during so-called seasons of risk (ie, periods in which individuals are at risk of acquiring infection). We refer to this as risk-informed PrEP. For each setting-scenario, we considered the situation in mid-2021 and performed a pairwise comparison of the outcomes of two policies: immediate PrEP scale-up and then continuation for 50 years, and no PrEP. We estimated the relationship between epidemic and programme characteristics and cost-effectiveness of PrEP availability to all during seasons of risk. For our base-case analysis, we assumed a 3-monthly PrEP cost of US$29 (drug $11, HIV test $4, and $14 for additional costs necessary to facilitate education and access), a cost-effectiveness threshold of $500 per disability-adjusted life-year (DALY) averted, an annual discount rate of 3%, and a time horizon of 50 years. In sensitivity analyses, we considered a cost-effectiveness threshold of $100 per DALY averted, a discount rate of 7% per annum, the use of PrEP outside of seasons of risk, and reduced uptake of risk-informed PrEP.FindingsIn the context of PrEP scale-up such that 66% (90% range across setting-scenarios 46-81) of HIV-negative people with at least one non-primary condomless sex partner take PrEP in any given period, resulting in 2·6% (0·9-6·0) of all HIV negative adults taking PrEP at any given time, risk-informed PrEP was predicted to reduce HIV incidence by 49% (23-78) over 50 years compared with no PrEP. PrEP was cost-effective in 71% of all setting-scenarios, and cost-effective in 76% of setting-scenarios with prevalence of HIV viral load greater than 1000 copies per mL among all adults higher than 2%. In sensitivity analyses with a $100 per DALY averted cost-effectiveness threshold, a 7% per year discount rate, or with PrEP use that was less well risk-informed than in our base case, PrEP was less likely to be cost-effective, but generally remained cost-effective if the prevalence of HIV viral load greater than 1000 copies per mL among all adults was higher than 3%. In sensitivity analyses based on additional setting-scenarios in which risk-informed PrEP was less extensively used, the HIV incidence reduction was smaller, but the cost-effectiveness of risk-informed PrEP was undiminished.InterpretationUnder the assumption that making PrEP easily accessible for all adults in sub-Saharan Africa in the context of community education leads to risk-informed use, PrEP is likely to be cost-effective in settings with prevalence of HIV viral load greater than 1000 copies per mL among all adults higher than 2%, suggesting the need for implementation of such approaches, with ongoing evaluation.FundingUS Agency for International Development, US President's Emergency Plan for AIDS Relief, and Bill & Melinda Gates Foundation.

Introduction: The Case Surveillance and Vital Registration (CSAVR) model within Spectrum estimates HIV incidence trends from surveillance data on numbers of new HIV diagnoses and HIV-related deaths. This article describes developments of the CSAVR tool to more flexibly model diagnosis rates over time, estimate incidence patterns by sex and age group and by key population group. Methods: We modelled HIV diagnosis rate trends as a mixture of three factors, including temporal and opportunistic infection components. The tool was expanded to estimate incidence rate ratios by sex and age for countries with disaggregated reporting of new HIV diagnoses and AIDS deaths, and to account for information on key populations such as men who have sex with men (MSM), males who inject drugs (MWID), female sex workers (FSW) and females who inject drugs (FWID). We used a Bayesian framework to calibrate the tool in 71 high-income or low-HIV burden countries. Results: Across countries, an estimated median 89% (interquartile range [IQR]: 7896-9696) of HIV-positive adults knew their status in 2019. Mean CD4 counts at diagnosis were stable over time, with a median of 456 cell/[micro]l (IQR: 391-508) across countries in 2019. In European countries reporting new HIV diagnoses among key populations, median estimated proportions of males that are MSM and MWID was 1.3% (IQR: 0.996-2.0%) and 0.5696 (IQR: 0.5196-0.6496), respectively. The median estimated proportions of females that are FSW and FWID were 0.3696 (IQR: 0.2796-0.4596) and 0.14 (IQR: 0.1396-0.1596), respectively. HIV incidence per 100 person-years increased among MSM, with median estimates reaching 0.43 (IQR: 0.29-1.73) in 2019, but remained stable in MWID, FSW and FWID, at around 0.12 (IQR: 0.04-1.9), 0.09 (IQR: 0.06-0.69) and 0.1396 (IQR: 0.0896-0.9196) in 2019, respectively. Knowledge of HIV status among HIV-positive adults gradually increased since the early 1990s to exceed 7596 in more than 7596 of countries in 2019 among each key population. Conclusions: CSAVR offers an approach to using routine surveillance and vital registration data to estimate and project trends in both HIV incidence and knowledge of HIV status. Keywords: HIV case-based surveillance; HIV incidence; HIV-related mortality; key population; knowledge of status; statistical models, 1 | INTRODUCTION The Joint United Nations Programme on HIV/AIDS (UNAIDS)-supported Spectrum software package is used by most countries in the world to generate annual estimates of HIV burden and [...]

1 | INTRODUCTION Sub-Saharan Africa (SSA) remains a region disproportionately affected by HIV. It is estimated that nearly 26 million people in this region are currently living with HIV with [...], Introduction: Oral pre-exposure prophylaxis (PrEP) is a new form of HIV prevention being considered for inclusion in nationa prevention portfolios. Many mathematical modelling studies have been undertaken that speak to the impact, cost and costeffectiveness 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. Keywords: PrEP; modelling; combination prevention; cost-effectiveness; sub-Saharan Africa

Introduction In the current global financial climate, it is more important than ever that effective resource allocation for the control of human immunodeficiency virus (HIV) infection is based on informed, [...], The modes of transmission model has been widely used to help decision-makers target measures for preventing human immunodeficiency virus (HIV) infection. The model estimates the number of new HIV infections that will be acquired over the ensuing year by individuals in identified risk groups in a given population using data on the size of the groups, the aggregate risk behaviour in each group, the current prevalence of HIV infection among the sexual or injecting drug partners of individuals in each group, and the probability of HIV transmission associated with different risk behaviours. The strength of the model is its simplicity, which enables data from a variety of sources to be synthesized, resulting in better characterization of HIV epidemics in some settings. However, concerns have been raised about the assumptions underlying the model structure, about limitations in the data available for deriving input parameters and about interpretation and communication of the model results. The aim of this review was to improve the use of the model by reassessing its paradigm, structure and data requirements. We identified key questions to be asked when conducting an analysis and when interpreting the model results and make recommendations for strengthening the model's application in the future. Le modele de modes de transmission a ete largement utilise pour aider les decideurs a cibler les mesures empechant l'infection par le virus d'immunodeficience humaine (VIH). Le modete estime le nombre de nouvelles infections par leVIH au cours de l'annee suivante, contractees par des individus appartenant aux groupes a risque identifies d'une population donnee, en utilisant des donnees sur la taille des groupes, le comportement a risque global de chaque groupe, la prevalence actuelle de l'infection par le VIH entre partenaires sexuels ou d'injection de drogues de chaque groupe, et la probabilite de transmission du VIH associee aux divers comportements a risque. La force du modele reside dans sa simplicite, permettant de synthetiser des donnees provenant d'une variete de sources, ce qui donne une meilleure caracterisation de I'epidemie du VIH dans certains contextes. Toutefois, des problemes ont ete releves concernant les hypotheses qui sous-tendent la structure du modele, les limites des donnees disponibles pour obtenir les parametres d'entree, ainsi que l'interpretation et la communication des resultats du modele. L'objectif de la presente etude etait d'ameliorer l'utilisation du modele en reevaluant son paradigme, sa structure et ses exigences en termes de donnees. Nous avons identifie les principales questions a poser lors de l'analyse et de l'interpretation des resultats du modele, et nous faisons des recommandations visant a renforcer l'application du modele a l'avenir. El modelo de los modos de transmision se ha empteado de manera cjeneralizada para ayudar a los responsables de la toma de decisiones a dirigir las medidas para la prevencion de la infeccion por el virus de la inmunodehciencia humana (VIH). El modelo calcula el numero de infecciones porVIH nuevas adquiridas durante el ano subsiguiente por individuos en grupos de riesgo identificados en una poblacion dada empleando datos acerca del tamano de los grupos, el comportamiento de riescjo conjunto en cada grupo, la prevalencia actual de la infeccion por VIH entre las parejas sexuales o personas que comparten jeringuillas para el consumo de drogas de los individuos de cada grupo y la probabilidad de trasmitir elVIH asociada a los diferentes comportamientos de riesgo. El punto fuerte del modelo es su sencillez, que permite sintetizar datos de fuentes variadas, de lo que resulta una caracterizacion mas exacta de la epidemia del VIM en algunos entornos. No obstante, han surgido dudas acerca de las suposiciones que subyacen a la estructura del modelo, las limitaciones de los datos disponibles para derivar de ellos parametros de entrada y la interpretacion y comunicacion de los resultados dei modelo. El objeto de este examen fue el de mejorar el uso del modelo volviendo a examinar su paradigma, su estructura y los requisitos de los datos. Identificamos los puntos clave que deben cuestionarse durante la realizacion de un analisis y la interpretacion de los resultados dei modelo y formulamos recomendaciones para consolidar la aplicacion del modelo en el futuro.

Introduction Since the announcement of the results of HIV pre-exposure prophylaxis (PrEP) trials and the HPTN052 early treatment for prevention trial, there have been crucial policy discussions about the use [...], Background:Cost-effectiveness studies inform resource allocation, strategy, and policy development. However, due to their complexity, dependence on assumptions made, and inherent uncertainty, synthesising, and generalising the results can be difficult. We assess cost-effectiveness models evaluating expected health gains and costs of HIV pre-exposure prophylaxis (PrEP) interventions. Methods and Findings:We conducted a systematic review comparing epidemiological and economic assumptions of costeffectiveness studies using various modelling approaches. The following databases were searched (until January 2013): PubMed/Medline, ISI Web of Knowledge, Centre for Reviews and Dissemination databases, EconLIT, and region-specific databases. We included modelling studies reporting both cost and expected impact of a PrEP roll-out. We explored five issues: prioritisation strategies, adherence, behaviour change, toxicity, and resistance. Of 961 studies retrieved, 13 were included. Studies modelled populations (heterosexual couples, men who have sex with men, people who inject drugs) in generalised and concentrated epidemics from Southern Africa (including South Africa), Ukraine, USA, and Peru. PrEP was found to have the potential to be a cost-effective addition to HIV prevention programmes in specific settings. The extent of the impact of PrEP depended upon assumptions made concerning cost, epidemic context, programme coverage, prioritisation strategies, and individual-level adherence. Delivery of PrEP to key populations at highest risk of HIV exposure appears the most cost-effective strategy. Limitations of this review include the partial geographical coverage, our inability to perform a meta-analysis, and the paucity of information available exploring trade-offs between early treatment and PrEP. Conclusions: Our review identifies the main considerations to address in assessing cost-effectiveness analyses of a PrEP intervention--cost, epidemic context, individual adherence level, PrEP programme coverage, and prioritisation strategy. Cost-effectiveness studies indicating where resources can be applied for greatest impact are essential to guide resource allocation decisions;however, the results of such analyses must be considered within the context of the underlying assumptions made. Please see later in the article for the Editors' Summary.