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The Consortium aims to be agile and responsive to new developments and help to fill the gaps that currently exist to support modelling research.

While many of the topics considered by the Consortium are novel and prompted by new innovations in discovery, funded work also intentionally promotes more groups looking at the same questions using different approaches. We also provide a forum for diverse research groups to be exposed to new expertise in adjacent disciplines and technological advances in software engineering and model design.

  • HIV Care Cascade

    Antiretrovirals for treatment of HIV are becoming increasingly available in sub-Saharan Africa, as we now understand that these drugs enable infected individuals to attain near natural life expectancy when administered optimally. To achieve such successful outcomes patients must pass through the ‘HIV care cascade’ via an ideal route. The optimum pathway includes early HIV testing, linkage to care, timely ART initiation and subsequent monitoring to assess adherence and ensure treatment continuation.

  • Improved Methods for Estimating HIV Prevalence and Incidence

    The international response to HIV relies on reliable estimates of the size of the epidemic and recent trends. These estimates are used for international resource mobilisation, national programme planning, evaluating the effectiveness of existing programmes, and policy planning and resource allocation. Current approaches to generating national HIV epidemic estimates in SSA use time series of HIV prevalence among pregnant women attending antenatal clinics (ANC) and prevalence among adults 15–49 y in nationally representative household surveys to estimate national HIV epidemic prevalence. Natural HIV progression and numbers on antiretroviral treatment (ART) are used to infer HIV incidence from this prevalence curve. In this work package we aim to understand if incorporating additional information into this process affects the estimates of HIV prevalence and incidence.

  • In-depth Model Comparison

    There were many questions raised in the comprehensive model comparison undertaken in work package on Treatment as Prevention when models did not produce similar outcomes even when simulated interventions were standardized. There are several hypotheses for these remaining differences and identifying the true root causes will be of substantial theoretical interest (in terms of identifying the influence of unsupported priors) as well as practical interest (so that results of simpler models can be confidently extrapolated). Building on sustained enthusiasm for the project, the Consortium has initiated a second concerted phase of model comparison which will be designed to tackle these issues.

  • Incidence Estimation

    Incidence estimation, in particular of HIV, continues to attract high interest and present enormous challenges. The theoretical basis for estimating incidence from cross sectional biomarker surveys has only recently been formalised. There appears to be the beginning of consensus on core concepts, an emerging sense of the possibilities and limitation, and no obvious scope for deep improvements in the demographic / epidemiological regime of HIV epidemiology. The immediate gap in current theory and practise is in the area of characterising the tests for recent infection from the usually considerably suboptimal data obtained in studies following seroconverters.

  • Integrated Pan-Continental Map of HIV Prevalence

    The geographic heterogeneity of the burden of the HIV epidemic within countries is receiving increasing attention. A recent modelling study of HIV in Kenya has indicated that targeting intervention strategies to prevalence "hotspots" may have a substantially greater impact on future incidence than a spatially uniform intervention programme at the same cost. There is a need to better understand the subnational heterogeneity in HIV prevalence in other African countries.

  • Investigating Reports of HIV Incidence Decline

    The 2012 UNAIDS Report on the Global AIDS Epidemic reported large declines in HIV incidence in a number of countries, both in Africa and globally. While these estimates have been promoted as evidence for the effectiveness of the international response to HIV/AIDS, in many settings these observed reductions were not coupled with changes in risk behaviour or large program efforts or scale up of ART, which may have been anticipated a priori. As such, the HIV Modelling Consortium were asked by the Steering Committee to explore potential mechanisms that (1) could reconcile the apparent discrepancy between these, or (2) could potentially lead to spurious or exaggerated estimates of declines in HIV incidence.

  • Methods for Sub-national Estimates of HIV Prevalence

    Major decisions in HIV programming planning and the impact evaluation of programs rely on understanding the epidemiology of HIV in a country. However, it is increasingly clear that substantial heterogeneity exists within a country in the extent of the HIV epidemic, its dominant modes of transmission and the implementation of programs. Existing surveillance, estimation and modelling is overwhelming focussed at the national level, but gaining a better understanding of the sub-national variation could be important for improving the efficiency and effectiveness of the response to HIV/AIDS epidemics. Consequently, country programmers and epidemiologists, as well as international funders, increasingly want to routinely use tools to measure, visual and analyse these within-country epidemiological patterns.

  • Modelling for the WHO 2013 Guidelines for Use of Antiretrovirals

    In July 2013 the WHO released major new guidance on the use of ART for HIV infection. The revised guidelines differed in content and format to previous guidelines as they focused on the programmatic aspects of implementing policy changes and provide a guide to staged and prioritized implementation. To support these efforts, mathematical modelling work has been introduced into the development of the guidelines for the first time.

  • Modes of Transmission Model

    To help optimize the allocation of resources in HIV prevention programmes, the UNAIDS/World Bank initiative ‘Know Your Epidemic – Know Your Response’ has been designed to facilitate programme managers to examine the sources of HIV infections in a country, which can then be used to guide prevention programme and data collection priorities.

  • Potential for Spread of Drug Resistance Due to PrEP

    A major concern in the use of ARV-drug in HIV-uninfected individuals to prevent HIV infection (Pre-Exposure Prophylaxis, PrEP) is the risk of generation of drug-resistant virus that compromises the efficacy of current first line treatment regimens.

  • Proposal for a revised Modes of Transmission Model

    The first work package initiated by the Consortium, Sources of Infection, reviewed different aspects of the Modes of Transmission model. As part of this project a number of research groups were award Request for Funding Applications to review the use and evaluate the utility of the Modes of Transmission model. The evaluative work identified some constraints of the existing model and it was agreed to extend this work package to a second phase in which the Secretariat would develop a proposal for a revised Modes of Transmission model.

  • Sexual Violence and HIV in Young Women

    There is a growing body of evidence that sexual violence exposes women to a higher risk of acquiring HIV infection. A combination of biological and behavioural factors could contribute to the increased susceptibility and could pose a potential explanation for the exceedingly high prevalence now observed among young women in sub-Saharan Africa.

  • The 'Freezer' Project

    Further to the Boston meeting entitled: Strengthening the Use of Mathematical Models in Community Trials, a proposal for a method of validating mathematical models models in this setting was characterised.

  • The Potential Impact of Treatment on HIV Incidence

    Recent epidemiological data have shown that HIV-infected individuals who take anti-retroviral therapy (ART) are substantially less likely to transmit HIV to their sexual partners. In light of this, many have endorsed expanding access to ART as a central component of HIV prevention strategies.

  • Validation Exercise Using Models Developed for Community Trials

    A number of trials started in late 2012 with a view to test key hypotheses about the impact of ART treatment on prevention of HIV. Mathematical modelling has played an important role in raising the hypotheses which these trials seek to test, and will be key to the design of trials and the interpretation of results. As the trials are taking place in a variety of settings, there will also be a need to understand how different results may be reconciled. The trials also provide an opportunity to draw a comparison between actual observed impact and model projections.

  • Value of Survey Information for Geographical Targeting Interventions

    This project, which is led by University of York, is the second element of a two-phased work package investigating how program planners may use data or methods that describe subnational heterogeneity of HIV epidemiology when developing their response to the epidemic. The first element focused on the development of optimal methodologies for determining the spatial heterogeneity based on current data, while this project aims to identify the value of collecting more precise estimates of epidemiological data on HIV so as to reduce decision uncertainty and errors.