Steve Bellan, MPH, PhD

Monday 2 June, 19:00, AIMS Main Lecture Hall

Abstract: For several decades it has been thought that much of HIV transmission occurs during the several month-long “acute phase” following infection, during which infected individuals are believed to be highly infectious. That so much transmission happens right after infection has been suggested to compromise the utility of antiretroviral treatment as prevention (TasP), which prevents transmission after, but not before, diagnosis and treatment. Whether acute transmission would undermine TasP has thus been the center of a large policy debate. Noting that the infectivity of acutely infected individuals had only been directly measured once, in a retrospective cohort study of couples in Rakai, Uganda, we reanalyzed this data but, unlike previous analyses, explicitly modeled the study design itself. We find that previously unaccounted for biases led multiple influential, prior analyses to substantially overestimate acute infectivity. Consequently, the proportion of HIV transmission that occurs too early to be preventable by TasP may thus be far smaller and give more optimism for TasP interventions.

About: Dr. Bellan is an Assistant Professor of Epidemiology and Biostatistics at the University of Georgia and the Program Director of the ICI3D program (since 2016). He has been involved as an organizer and instructor of the MMED and DAIDD clinics since 2009, after attending precursor workshops in 2007-2008 as a student. Steve’s background includes logistically challenging field work studying anthrax and rabies outbreaks in Namibian wildlife, as well as experience with a variety of mathematical, statistical and computational methods. His research projects span numerous pathogens and are united under the overarching theme of using mechanistic modeling and high performance computing to plan and interpret empirical studies. One of Steve’s current projects centers on understanding heterogeneity in HIV transmissibility across individuals, explaining the dramatic variation in HIV epidemic severity across Africa. A second research focus aims to optimally navigate the scientific and ethical tradeoffs involved in vaccine efficacy trials during emerging epidemics of pathogens such as the Ebola and Zika viruses.