Modelling mobility and HIV epidemics in sub-Saharan Africa

Over 25 million people with HIV (PWH) live in sub-Saharan Africa (SSA), where epidemics are generalized and driven by heterosexual transmission. HIV treatment based on antiretrovirals is now widely used throughout SSA, and UNAIDS has set a goal for achieving HIV elimination by 2030. That goal is unlikely to be achieved, because empirical data show that transmission is still ongoing; however many models are predicting that HIV elimination will occur fairly soon. In my talk, I will discuss how the disconnect between the data and the modeling predictions is due to the fact that the models do not take population mobility into account. All of the models are based on the assumption that HIV transmission is localized; i.e., that people only have sex with people that are close to home. I will present a series of studies that my research group has conducted that show that this assumption is erroneous, and that both localized and mobility-driven transmission need to be taken into consideration. I will show that the mobility of populations in SSA have dramatic effects on the epidemiology of HIV, and that elimination cannot occur (in the real-world) unless novel mobility-focused control strategies are developed. Mobility changes who is at-risk, who is transmitting, and where transmission occurs. I will present four studies, each of which focuses on the impact of mobility in different countries in SSA: Lesotho, Botswana, Namibia, and Malawi. All four studies address different research questions, and use a variety of geospatial models and geostatistical analyses. I will then discuss how these studies can be used to develop a new generation of HIV transmission models for SSA, and the implications of their results for the elimination of HIV in the real-world.