Department of Gastroenterology;
401 General Military Hospital of Athens;
Athens 11525;
Attiki;
Greece;
Medical Office of Hellenic Army General Staff;
401 General Military Hospital of Athens;
Athens 11525;
Attiki;
Greece;
Laboratory of Biology;
School of Medicine;
National and Kapodistrian University of Athens;
Athens 11527;
Attiki;
Greece;
SARS-CoV-2; COVID-19; Gastrointestinal tract; Angiotensin converting enzyme type 2; Angiotensin converting enzyme type 2 receptor; Renin-angiotensin system; Angiotensin converting enzyme;