1. Directorate of Research, Studies, and Documentation, National Public Health Organization, Athens, Greece
2. Directorate of Epidemiological Surveillance of Infectious Diseases, National Public Health Organization, Athens, Greece
3. Medical Oncology Department, Venizeleio-Pananeio General Hospital, Heraklion, Greece
4. Pathophysiology Department, Medical School, National and Kapodistrian University of Athens, and General Hospital of Athens Laiko, Athens, Greece
5. First Department of Pediatrics, University of Athens, Aghia Sophia Children’s Hospital, Athens, Greece
6. Infection Control Committee, Venizeleio-Pananeio General Hospital, Heraklion, Greece
7. COVID-19 Intensive Care Unit, 424 General Military Hospital of Thessaloniki, Thessaloniki, Greece
8. Infection Control Committee, Korgialeneio-Benakeio Red Cross General Hospital, Athens, Greece
9. Department of Microbiology, Venizeleio-Pananeio General Hospital, Heraklion, Greece
10. Occupational Medicine Unit, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
11. Department for Travel Medicine, National Public Health Organization, Athens, Greece
12. Internal Medicine and Infectious Diseases Clinic, Iatriko Athinon General Hospital, Athens, Greece
13. Department of Pediatrics, University of Thessaly, Larissa, Greece
14. Infectious Diseases Unit, First Department of Internal Medicine, Gennimatas General Hospital, Athens, Greece
15. Third Department of Internal Medicine and Infectious Diseases Unit, Korgialeneio-Benakeio Red Cross Hospital, Athens, Greece
16. Infection Prevention and Control Committee, Aghia Sofia Children’s Hospital, Athens, Greece
17. Medical Directorate, Hellenic Air Force General Staff, Athens, Greece