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sempaj@sun.ac.za

Joseph Sempa, PhD

Postdoctoral Research Fellow

Postdoctoral Research Fellow

Dr Joseph B Sempa is a Research associate at SACEMA, working on the repurposing of HIV diagnostic assays for HIV management and is supervised by Prof Alex Welte. Joseph’s work focuses on how HIV serological assay results can be used to estimate time since HIV infection in newly diagnosed HIV patients. This is important in achieving the first 90-90-90 UNAIDS goal of HIV testing 90% of the population as time since HIV infection in newly diagnosed patients can be used for contact tracing, support for disclosure to partners, and preparing people for treatment.

Further, Joseph was recently shortlisted for the EDCTP career development fellowship to analyze and interpret the dynamic range of HIV diagnostic assays for viral load monitoring after antiretroviral therapy initiation. This work will focus on HIV antibody monitoring can be used in place of viral load monitoring when patients are on ART. Previously, he was funded by SACEMA to do a PhD in Epidemiology, focusing on the effects of longitudinal HIV viral load on treatment outcomes in people on ART in sub-Saharan Africa, under the supervision of Prof Martin Nieuwoudt. He attended MMED in 2013 after which he received an ICI3D scholarship under the supervision of Prof Steve E Bellan.

Recent publications

Pearson, C. A. B., C. van Schalkwyk , A.M. Foss , K.M. O'Reilly , R. Beauclair , E.B. Are , O.O. Adetokunboh, J. Bingham, C.M. Hazelbag, I. Kombe, B.J. Sempa, & J.R.C. Pulliam, E.S. Nightingale, S. Funk, R.M. Eggo , J. Hellewell, A.J. Kucharski, Q.J. Leclerc , N.G. Davies, J.C. Emery, S. Flasche, N.I. Bosse , S. Abbott, M. Auzenbergs, A. Gimma, S.R. Procter, R.M.G.J. Houben , T.W. Russell, A. Endo, C. Diamond, J.D. Munday, G. Knight, F.Y. Sun, Y. Liu, A.K. Deol, T. Jombart , B.J. Quilty, S. Clifford , P. Klepac , K. van Zandvoort, K. Prem, A. Rosello, G. Medley, M. Jit, C.I. Jarvis, H. Gibbs, & W.J. Edmunds (2020) Projected early spread of COVID-19 in Africa through 1 June 2020. Eurosurveillance 25(18) 2000543 doi: 10.2807/1560-7917.ES.2020.25.18.2000543


Sempa, J.B., T.M. Rossouw, E. Lesaffre, & M. Nieuwoudt (2019) Cumulative viral load as a predictor of CD4+ T-cell response to antiretroviral therapy using Bayesian statistical models. PloS one 14(11):e0224723. doi: 10.1371/journal.pone.0224723


Sempa J.B., A. Welte, M.P. Busch, J. Hall, D. Hampton, S.N. Facente, .S.M Keating, K. Marson, N. Parkin, C. D. Pilcher, G. Murphy, & E. Grebe (2019) Performance comparison of the Maxim and Sedia Limiting Antigen Avidity assays for HIV incidence surveillance. PloS one 14(7):e0220345 doi: /10.1101/572677


Sempa, J.B., E.L. Ujeneza, & M. Nieuwoudt (2017) Systematic review of statistically-derived models of immunological response in HIVinfected adults on antiretroviral therapy in Sub-Saharan Africa. PLOS ONE 12(2): e0171658. doi: 10.1371/journal.pone.0171658


Sempa, J.B., J. Dushoff, M.J. Daniels, B. Castelnuovo, A.N. Kiragga, M. Nieuwoudt & S.E. Bellan (2016) Reevaluating Cumulative HIV-1 Viral Load as a Prognostic Predictor: Predicting Opportunistic Infection Incidence and Mortality in a Ugandan Cohort. American journal of Epidemiology 184(1):67-77. doi: 10.1093/aje/kwv303


DSI-NRF Centre of Excellence in Epidemiological Modelling and Analysis