1. Usher Institute, University of Edinburgh, Edinburgh, UK
2. School of Biological Sciences, University of Edinburgh, Edinburgh, UK
3. The Roslin Institute, University of Edinburgh, Edinburgh, UK
4. Clinical Infection Research Group, Regional Infectious Diseases Unit, Western General Hospital, UK
5. Department of Medicine, Division of Infectious Diseases, Imperial College London, UK
6. Centre for Mathematical Modelling of Infectious Disease, London School of Hygiene and Tropical Medicine, London, UK