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.


Mathematical modellers have considered the potential impact of ART on HIV incidence and prevalence in a variety of scenarios and settings over the past 15 years, with model estimates becoming more refined as improved data have become available.  


In order to investigate the potential effectiveness of ‘treatment as prevention’ and identify an agenda of high-priority research for policy makers, we facilitated a meeting of over 50 modellers, prevention scientists, program implementers, and decision makers in Stellenbosch, South Africa in 2011. In advance of the meeting, we coordinated a novel exercise to systematically compare predictions of twelve independently developed models of the impact of ART on new HIV infections in South Africa. 

Aims of Meeting

  1. Systematically compare existing mathematical models of expanded HIV treatment for prevention and identify the extent to which they agree and understand the reasons for any discrepancies in model predictions.
  2. Identify aspects of treatment intervention programmes that may not be adequately addressed in existing modelling, and create a research agenda for incorporating these.
  3. Create a joint statement identifying key data needs for improving the specificity of mathematical models.
  4. Identify and prioritise research of most urgent programmatic importance.


  • Following the meeting, the Consortium produced a special collection of papers in the journal PLOS Medicine examining different aspects and considerations around HIV treatment as prevention which was launched at the XIX International AIDS Conference in Washington DC. PLoS Medicine Special Collection with the HIV Modelling Consortium
  • Hontelez J, et al. Elimination of HIV in South Africa through Expanded Access to Antiretroviral Therapy: A Model Comparison Study. PLoS Med 10(10): e1001534. doi:10.1371/journal.pmed.1001534

Funding issued

MC 3.1: PI Wim Delva - SACEMA

MC 3.2 PI Gesine Meyer-Rath - Boston University

MC 3.2: PI Sake J De Vlas - Erasmus Medical Centre

MC 3.3: PI Till Bärnighausen - Africa Centre