1. Find and Treat, University College London Hospitals NHS Foundation Trust, London, UK
2. University College London Centre for Infectious Disease Epidemiology, Department of Infection and Population Health, London, UK
3. University College London Centre for Infectious Disease Epidemiology, Department of Infection and Population Health, London, UK; Respiratory Diseases Department, Health Protection Services, Health Protection Agency, London, UK
4. Centre for Respiratory Medicine, University College London, Royal Free London, NHS Foundation Trust, London, UK
5. Respiratory Diseases Department, Health Protection Services, Health Protection Agency, London, UK