1. COVID‐19 Unit, GNDA “Agia Varvara” Hospital Athens Greece
2. 2nd Respiratory Medicine Department General University Hospital “Attikon”, Medical School, National and Kapodistrian University of Athens Athens Greece
3. Department of Respiratory Medicine, General Hospital G. Papanikolaou Pulmonary Department of Aristotle University of Thessaloniki Thessaloniki Greece
4. Respiratory Medicine Department University of Ioannina, Faculty of Medicine Ioannina Greece
5. 4th Respiratory Medicine Department Sotiria Hospital Athens Greece
6. 4th Internal Medicine Department General University Hospital “Attikon”, Medical School, National and Kapodistrian University of Athens Athens Greece