He has studied and published in many areas of science: physics, chemistry, statistics, epidemiology, entomology, ecology, social sciences and public health. The unifying theme in his scientific life has been mathematics and statistics with a special emphasis on modelling dynamical systems. 

Most recently He have worked extensively on HIV, TB and SARS-Covid2 with a particular interest in using dynamical models to understand time trends in the epidemics of both diseases, to explore different ways in which we might be able to control diseases, to make future projections under different scenarios, to provide advice to policy makers at a national and an international level while taking cognizance of the social determinants of disease and the importance of dealing with the issues that they raise.