An overview of COVID-19 global epidemiology and discussion of potential drivers of variable global pandemic impacts.

With a WHO-estimated excess mortality burden of 14.9 million over the course of 2020 and 2021, the COVID-19 pandemic has had a major human impact so far. It has also affected a range of disciplines, systems and practices from mathematical modelling to behavioural sciences, pharmaceutical development to health system management. This article explores these developments and, to set the scene, this paper summarizes the global epidemiology of COVID-19 from January 2020 to June 2021 and considers some potential drivers of variation.