Before joining APHRC, he had worked with the UK Medical Research Council Unit in Uganda (2008-2015) leading epidemiological studies including clinical trials on HIV and non-communicable diseases in Uganda. As a technical advisor for the Columbia University-ICAP program (2015-2017), he led the national Population-based HIV Impact Assessment (PHIA) in Uganda and supported PHIAs in Cameroon and Namibia. He had worked as a frontline physician in Uganda (2001-2006). Since 2014, he has been at the forefront of developing digital platforms including fingerprint technology and mobile phone applications to improve access to healthcare such as improving safe deliveries in health facilities, timely administration of vaccinations and self-management of chronic diseases among vulnerable populations. 

He has held several grants and successfully managed a number of research projects on chronic diseases (HIV, non-communicable diseases and neglected tropical diseases). He is very well networked with other researchers globally, program implementers and policy-makers in Africa. He has over 70 peer-reviewed journal articles and is co-editor of a recently published book: “Handbook of Global Urban Health”. He is also an Associate Editor on the East African Journal of Applied Health Monitoring and Evaluation. He regularly contributes to the APHRC flagship program for strengthening research capacity across Africa through training and mentoring junior researchers in academic writing.  

Gershim received the Erasmus Mundus Scholarship award for his Masters (2007), HIV Research Trust Scholarship fund for strengthening data analysis in Health and Demographic Surveillance Systems (2013), a fellowship by University of California, San Francisco (UCSF) under the UCSF ITAPS and Fogarty International Center Programs for training and certification as a mentor for scientific writing (2015). Recently he received the African Research Excellence Fund (AREF) award by the UK Medical Research Foundation for research leadership development (2018).