1. Health Protection Agency, Hampshire and Isle of Wight Health Protection Unit, Unit 8, Fulcrum 2, Solent Way, Whiteley, Hampshire PO15 7FN, UK
2. Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, University Hospital Southampton Foundation NHS Trust, South Academic Block, Southampton SO16 6YD, UK
3. Academic Unit of Primary and Population Sciences, Faculty of Medicine, University of Southampton, University Hospital Southampton Foundation NHS Trust, South Academic Block, Southampton SO16 6YD, UK
4. HPA Public Health Laboratory, Southampton Laboratory Level B, South Pathology Block, University Hospital Southampton Foundation NHS Trust, Southampton SO16 6YD, UK
5. NIHR Respiratory Biomedical Research Unit, University Hospital Southampton Foundation NHS Trust, Southampton SO16 6YD, UK
6. NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton Foundation NHS Trust, Southampton SO16 6YD, UK
7. Grove Medical Practice, Shirley Health Centre, Grove Road, Southampton SO15 3UA, UK
8. Institute of Public Health, College of Medicine & Health Sciences, UAE University, PO Box 17666, Al Ain, United Arab Emirates