This article is based on the presentation given by John Hargrove at the NRF Science for Society Lecture entitled Ending HIV/AIDS in South Africa held on 1 December 2016 in Stellenbosch. He argues that the proactive use of ART (Treatment as Prevention or TasP) provides a powerful weapon for combatting the HIV epidemic, and that we also have the tools for monitoring and evaluating the progress of that programme. Mathematical modelling has played an important role, both in suggesting appropriate interventions, and in developing new monitoring methods, but we are still in for a long journey.
Treatment As Prevention
Antiretroviral therapy (ART) markedly reduces the risk of sexual transmission of HIV. This inspired the idea of treatment as prevention (TasP) to reduce population HIV incidence, by reducing the infectiousness of HIV-infected individuals. However, increased infectiousness when treated individuals are co-infected with other sexually transmitted infections (STIs) could potentially undercut the effectiveness of TasP programs. As there is limited knowledge about the impact of STI co-infections on HIV shedding from individuals on ART, this study reviewed all published scientific evidence.
At the 3rd International HIV Treatment as Prevention Workshop in Vancouver, Canada, in April 2013 I was asked to put forward the case that “Pre-Exposure Prophylaxis (PreP) is not an essential component of Treatment as Prevention (TasP)”. So my job was to convince the public that while PreP may be a useful, and even an important, addition to TasP it is by no means an essential component of TasP. Here I reproduce my argument and invite readers of the SACEMA Quarterly to express their own views on this important issue.
My motivation to plan for the mathematical modelling of the HIV epidemic in Viet Nam has been to demonstrate the benefits of earlier initiation of antiretroviral treatment (ART). I especially wanted to estimate the potential impact of ART to prevent HIV transmission in communities. I hoped that the results would potentially influence the society to become more serious in creating an environment in which people feel safe to access HIV testing and counselling and treatment early, especially for the people who inject drugs and other groups who have a high HIV incidence. Here I tell you my journey to realize my plan.
In the SACEMA Quarterly we regularly report on issues (effects, costs) related to universal access to antiretroviral treatment (ART) or treatment as prevention (TaP). A recently published article focuses on the human resources needed for this approach. This because availability of human resources may now be the most important barrier to achieving universal access to Read More
AIDS 2012 has come and gone. South African researchers and NGOs engaged in AIDS related work were ever visible, presenting new results, chairing key sessions, or delivering invited talks. Before the conference began, it was widely noted that an important shift in debate has occurred in recent years, concerning the coalescence of treatment and prevention. The real discussion is now much more about how, practically, to access the prevention benefit of treatment. This debate, at AIDS 2012, although heated at times, at least did not just go over the same old ground. Furthermore, the progress here has largely been based on the work of South Africans pushing these ideas, and amassing the evidence of early impact of our local treatment programme. It must be said that South Africans are doing some of the most important work in many aspects of HIV research, not just in applications to our specific problems, but also raising the bar internationally in the practice of good science.
The role of treatment as prevention / the test and treat strategy to reduce the HIV incidence continues to be a hot topic
The current issue of the SACEMA Quarterly focuses on research findings on South Africa that have been presented at the 19th Conference on Retroviruses and Opportunistic Infections (CROI) that was held from 5-8 March 2012 in Seattle. The role of treatment as prevention and combining different strategies to reduce the HIV incidence continue to be hot topics. The study by Ramzi Alsallaq et al. focuses on mathematical modelling on the impact of combined interventions on the short- and long-term incidence of HIV in KwaZulu-Natal. As this is just one of the large number of mathematical models predicting the incidence of HIV in South Africa, the HIV Modelling Consortium brought together mathematical modellers to do a model comparison exercise to see what the potential role is of HIV treatment as prevention in South Africa. The results are presented by Jeff Eaton at al. Finally, the article of Stephane Verguet is focussing on how best to assess the (cost-)effectiveness of different HIV treatment programs and models so that the existing limited resources can be allocated optimally.
Many mathematical models have investigated the impact of HIV treatment as prevention in combination with other prevention strategies or other guidelines for HIV treatment provision. Generally, all models have predicted positive prevention benefits of HIV treatment, but directly comparing the results of different models has been challenging because each model has been used to answer different questions and has reported different key outcomes. In November 2011, the HIV Modelling Consortium convened a meeting with the aim to understand the extent to which different mathematical models agree about the potential impact of HIV treatment. The results of a model comparison exercise – in which each of the models simulated a standardised set of HIV intervention scenarios and reported common metrics of intervention impact – are reported here.
Household surveys estimate the proportion of HIV infected persons in KwaZulu-Natal at a level of ~23% of the population. What is urgently needed is to seek ways to reduce HIV incidence while caring for existing infections in KZN. The emerging course of action against HIV spread is to use a combination of prevention interventions rather than relying on individual tools. This article discusses mathematical modelling conducted to forecast the impact of combined interventions at both the short- and long-term. The modelling shows the importance of repeated high coverage of testing, linkage to care, starting treatment on time (at CD4 count 350 or less), and high coverage of circumcision in order to reduce the rate of HIV infection in KZN.