1 Department of Woman and Child Health and Publich Health, Fondazione Policlinico Universitario A Gemelli IRCCS, Rome, Italy; Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, 00168 Rome, Italy.
2 SAPPHIRE Group, Health Sciences, Leicester University, Leicester, UK; Paediatric Emergency Medicine Leicester Academic Group, Children's Emergency Department, Leicester Royal Infirmary, Leicester, UK.
3 RCEMLearning, Royal College of Emergency Medicine, London, UK.
4 Division of Child Health, Obstetrics and Gynaecology, School of Medicine, University of Nottingham, Nottingham, UK.
5 Paediatric Accident and Emergency, Royal London Hospital, London, UK.
6 Paediatric Emergency, Royal London Hospital, London, UK; Paediatric Emergency Department, Queen Mary University of London, London, UK. Electronic address: tessa.davis@nhs.net.