1. University of Oxford, Oxford, United Kingdom;
2. Health Protection Agency, London, United Kingdom;
3. University of Nottingham, Nottingham, United Kingdom;
4. Health Protection Services Scotland, Glasgow, United Kingdom;
5. Health Protection Team (North Wales), Mold, United Kingdom;
6. Cardiff University, Cardiff, United Kingdom;
7. Thames Valley Local Health Protection Unit, Aylesbury, United Kingdom;
8. St Thomas' Hospital, Stockport, United Kingdom;
9. Health Protection Agency Southwest, Stonehouse, United Kingdom