inclusion criteria: - within 7 days of patient's need of oxygen supply - positive sars-cov-2 rt-pcr - at least one risk factor for bad prognosis of covid-19: moderate-severe asthma, diabetes mellitus, cardiac conditions (congestive heart failure, coronary disease, cardiomyopathy, pulmonary hypertension), severe obesity (bmi>40), age>65, immunodeficiency, chronic liver disease. - respiratory insufficiency : room air spo2 <94% or pao2/fio2<300mmhg - age>18 - ability to sign an informed consent

inclusion criteria: - within 7 days of patient's need of oxygen supply - positive sars-cov-2 rt-pcr - at least one risk factor for bad prognosis of covid-19: moderate-severe asthma, diabetes mellitus, cardiac conditions (congestive heart failure, coronary disease, cardiomyopathy, pulmonary hypertension), severe obesity (bmi>40), age>65, immunodeficiency, chronic liver disease. - respiratory insufficiency : room air spo2 <94% or pao2/fio2<300mmhg - age>18 - ability to sign an informed consent