Tweya was selected on the basis of his research work in Malawi since 2006, when he began participating in a national antiretroviral therapy survey of healthcare workers. He has been involved in other studies as a lead author and has been involved in training other people to conduct operational research.
Tweya started as a Junior Operational Research fellow in 2009 and was promoted to Senior OR fellow in April 2011. As a fellow, he is required to conduct research and submit two papers each year for publication. Tweya's research through the Union programme has ranged from determining the incidence of pregnancy among women on ART in urban Malawi to assessing TB treatment outcomes of new smear-positive TB patients in relation to their HIV status. One of his papers has already been published in Tropical Medicine and International Health. He has also participated in a series of published studies on access to antiretroviral treatment and outcomes for special populations in Malawi, including teachers, police, the defence forces, prisoners and healthcare workers.
Tweya completed a BSc in statistics and computer science from the University of Malawi Chancellor College in 2005 and obtained an MSc in Epidemiology from the London School of Hygiene and Tropical Medicine in 2010. In addition to his work as a Union fellow, he has been Monitoring and Evaluation Officer for Lighthouse Clinic in Lilongwe, Malawi since 2006. His areas of expertise include designing qualitative and quantitative research tools in health related areas; managing large databases for programme monitoring; and quantitative analysis of both cross-sectional and longitudinal data.