1. Department of Medicine, School of Clinical Medicine, University of Cambridge, Hills Road, Cambridge CB2 2SP, United Kingdom
2. Peter Medawar Building for Pathogen Research, Nuffield Department of Clinical Medicine, University of Oxford, South Parks Road, Oxford OX1 3SY, United Kingdom
3. Centre for Applied Medical Statistics, Department of Public Health and Primary Care, University of Cambridge, Hills Road, Cambridge CB2 2SP, United Kingdom