1. Imperial College London, London, U.K.
2. Chelsea and Westminster NHS Foundation Trust, London, U.K.
3. London School of Hygiene & Tropical Medicine, London, U.K.
4. St Mary's Hospital, Imperial College Healthcare NHS Trust, London, U.K.
5. The Hillingdon Hospitals NHS Foundation Trust, Uxbridge, U.K.
6. London North West University Healthcare NHS Trust, London, U.K.