Gordon Dougan FRS is a Professor in the Department of Medicine, University of Cambridge and has spent his career leading research into vaccines, pathogen genomics and disease tracking. His research work has helped to redefine our understanding of how infections spread around the world, a subject of direct relevance to the current Covid-19 epidemic. These are his personal thoughts on the COVID-19 epidemic (https://en.wikipedia.org/wiki/Gordon_Dougan).