Informing the treatment and prevention response for HIV among people who inject drugs: a case study of South Africa

Drug use is a major public health concern globally, while people who inject drugs (PWID) have a heightened risk of acquiring human immunodeficiency virus (HIV) and are also thought to have poorer HIV treatment outcomes. In South Africa, the provision of HIV treatment and prevention interventions for PWID is limited, while structural factors such as homelessness are highly prevalent. In this doctoral research, I investigate the evolving illicit drug use in South Africa and give insights into improving the treatment and prevention response for the HIV epidemic among PWID, with a case study of South Africa. First, I used data from five population-based household surveys to assess the trends and predictors of drug use and evaluate how drug use is associated with worse health and HIV outcomes in South Africa. I find that drug use has increased 7-fold over 2002-2017, including in opioid use and is associated with higher sexual risk behaviours and some health outcomes. Secondly, I undertook the first ever global systematic review and meta-analysis to quantify HIV viral suppression among PWID and compare outcomes with other population groups. I find that PWID living with HIV and those on antiretroviral therapy (ART) have 46-86% lower viral suppression than the general population and men who have sex with men. Lastly, I develop the first mathematical model of HIV transmission among PWID in South Africa, for Pretoria, and assess the potential impact of scaling up ART, needle and syringe programme (NSP) and opioid agonist therapy (OAT), and/or reducing levels of homelessness among PWID. I find that removing the detrimental effects of homelessness could avert a third of new HIV infections over 2023-2030, whilst scaling up ART, NSP, and OAT and providing housing interventions for homeless PWID could avert two-thirds of new HIV infections and reduce incidence by 80% over 2023-2030.