I am an epidemiologist at the University of Bristol Medical Research Council Integrative Epidemiology Unit, UK and the University of Pennsylvania Perelman School of Medicine, USA. My research covers causal inference using electronic health record data and Mendelian randomization, particularly for the study of drug effects. Since late 2020, I have been conducting COVID-19 research in national secure data environments that provide access to population-level electronic health record data. I also work closely with the Damrauer lab at the University of Pennsylvania on projects using Mendelian randomization in the Million Veteran Program data.