1. Statistics, Modelling, and Economics Department, National Infection Service, Public Health England, London, United Kingdom
2. Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
3. PICANet, School of Medicine, University of Leeds, Leeds, United Kingdom
4. Immunisation and Countermeasures Department, National Infection Service, Public Health England, London, United Kingdom