Professor Simbayi is the Acting Chief Executive Officer (CEO) of the Human Sciences Research Council (HSRC) of South Africa since 1 April 2021. He is formerly the founding Executive Director of the HIV/AIDS, STIs and TB (HAST) research programme in the same organisation, a position which he held since its founding in July 2010 until 31 December 2015. Between February 2008 and June 2009 he also served as the Acting Executive Director of the Social Aspects of HIV/AIDS and Health (SAHA) programme, followed by one year as the Executive Director from July 2009 until June 2010. From the time that he joined the HSRC on 1 November 2001 until June 2007, he served as a Research Director in charge of the Behavioural and Social Aspects of HIV/AIDS Research Unit in SAHA as well as the Regional Coordinator for Southern Africa of the Social Aspects of HIV/AIDS Research Alliance (SAHARA). From July 2007 until June 2009 he also served as the Deputy Executive Director of the then SAHA research programme.
Professor Simbayi holds a Doctor of Philosophy (D.Phil.) degree in Experimental Psychology from the University of Sussex in England, United Kingdom. He is a registered Research Psychologist with the Health Professions Council of South Africa's Professional Board of Psychology and also a Member of Academy of Science of South Africa (ASSAf). He is also currently an Honorary Professor in the Department of Psychiatry and Mental Health at the University of Cape Town. He is also a National Research Foundation (NRF)-rated researcher
Before joining the HSRC, Professor Simbayi spent 15 years as an academic during which time he taught mainly courses in research methods and statistics in psychology, and biological psychology at both undergraduate and postgraduate levels at five different universities in Southern Africa, namely, Universities of Zambia, Bophuthatswana (now North West University, Mahikeng Campus), Port Elizabeth (now Nelson Mandela University, South Campus), Fort Hare, and Western Cape (UWC). He was Associate Professor and Head of Psychology Department at Fort Hare, and Associate Professor and then full Professor as well as Chairperson of the Department of Psychology at UWC.
During the past two decades Professor Simbayi has mostly conducted his research in the area of social aspects of HIV/AIDS and sexually transmitted infections (STIs). In particular, his research has focused on second-generation HIV surveillance especially using biobehavioural surveys, HIV/AIDS-related stigma and discrimination, orphans and vulnerable children (OVC), determinants of HIV infection (such as poverty, alcohol and drug use, gender-based violence, sex in the presence of blood, multiple sexual partnerships, and male circumcision), and theory-based HIV social and behavioural risk reduction interventions including positive prevention which targets people living with HIV/AIDS who are aware of their status.
Prof Simbayi has published 138 scientific articles in both local and international peer-reviewed academic journals, 26 research reports, 15 abstracts, and 12 book chapters. He co-edited a book entitled HIV/AIDS in South Africa 25 Years on: Psychosocial Perspectives which was published by Springer of New York in 2009. He has also presented more than 300 papers and posters at both local and international conferences. He is an Associate Editor of the Journal of Psychology in Africa.