1. Hellenic Thoracic Society (HTS), Infectious Diseases Working Group, Athens, Greece
2. 6th Respiratory Medicine Department, “Sotiria” Hospital of Chest Diseases, Athens, Greece
3. Department of Respiratory Medicine, University Hospital of Ioannina, Loannina, Greece
4. Pfizer Greece, Vaccines, Athens, Greece
5. Pfizer Spain, Vaccines, Madrid, Spain
6. Pfizer Ltd, Global Vaccines, Medical Development and Scientific/Clinical Affairs (MDSCA), London, United Kingdo
7. Pfizer Inc., Global Vaccines, Collegeville, Pennsylvania, United States of America
8. 1st Internal Medicine Department, University Hospital of Ioannina, Loannina, Greece
9. 2nd Internal Medicine Department, University Hospital of Ioannina, Loannina, Greece
10. Internal Medicine Department, General Hospital of Ioannina G. Hatzikosta, Loannina, Greece
11. 1st Respiratory Medicine Department, General Hospital of Kavala, Kavala, Greece
12. 2nd Respiratory Medicine Department, General Hospital of Kavala, Greece