1. Department of Paediatrics, UCLH Hospitals NHS Foundation Trust, London, United Kingdom
2. Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
3. Department of Paediatrics, Northwick Park NHS Trust, London, United Kingdom
4. Department of Paediatric Infectious Diseases, Evelina Children’s Hospital, Guys and St Thomas’ NHS Foundation Trust, London, United Kingdom.