1. National Institute for Health Research (NIHR) Health Protection Research Unit in Modelling Methodology and Medical Research Council Centre for Outbreak Analysis and Modelling, Imperial College London School of Public Health;
2. Modelling and Economics Unit, National Infection Service, Public Health England, London;
3. Institute of Applied Health Research, University of Birmingham; and
4. NIHR Health Protection Research Unit in Evaluation of Interventions, University of Bristol, United Kingdom