Inclusion Criteria:  COVID-19 positive patients: hospitalised patients diagnosed with COVID-19 in one of the investigating sites, and able to provide a stool sample. Control subjects: Medical and paramedical personnel working at one of the investigating sites, having been in direct contact with the patients. Aged between 18 and 95 years. Subjects able to read the French-language study information leaflet. Patients with social cover.  Exclusion Criteria:  COVID-19 negative patients. Patients in critical care, heart failure or respiratory failure. Unable to provide naturally a stool sample. Patients without social cover. Pregnant women