1. Department of Paediatrics, Evelina Children's Hospital, St Thomas' Hospital, Guy's and St Thomas' National Health Service (NHS) Foundation Trust, London, United Kingdom
2. South London Specialist Virology Centre and Health Protection Agency, King's College Hospital NHS Foundation Trust, London, United Kingdom
3. Department of Paediatrics, Newham University Hospital NHS Trust, London, United Kingdom
4. Department of Paediatrics, Central Middlesex Hospital Sickle and Haemoglobinopathy Centre, North West London Hospitals NHS Trust, London, United Kingdom
5. Department of Paediatric Haematology, King's College London School of Medicine, King's College Hospital, London, United Kingdom
6. Paediatric Infectious Diseases Unit, St Georges' Hospital, London, United Kingdom
7. Department of Paediatrics, Mayday University Hospital NHS Trust, London, United Kingdom
8. Queen Elizabeth Hospital, South London Healthcare NHS Trust, London, United Kingdom
9. Department of Paediatrics, North Middlesex Hospital in partnership with Great Ormond Street Hospital, London, United Kingdom