1. COVID‑19 Reference Centre, ‘Rafina’ Health Care Centre, 19009 Rafina, Greece
2. Paediatric Intensive Care Unit (PICU), University Hospital of Patras, 26504 Rio, Greece
3. Department of Paediatric Radiology, ‘Mitera’ Children's Hospital, 15123 Athens, Greece
4. Department of Paediatrics, ‘Penteli’ Children's Hospital, 15236 Palaia Penteli, Greece
5. Institute of Paediatric Virology, Aliveri, 34500 Island of Euboea, Greece