inclusion criteria: * age \> 18 years * diagnosis of pneumonia caused by covid-19 * respiratory and/or systemic symptoms and initial mild respiratory failure and with objective signs of lung involvement * respiratory frequency ≥25/min, blood oxygen saturation (sao2) \< 95% in a-a, pao2/fio2 ratio \< 300 * hospital admission since less than 48 hours * signature of informed consent for study participation

inclusion criteria: * age \> 18 years * diagnosis of pneumonia caused by covid-19 * respiratory and/or systemic symptoms and initial mild respiratory failure and with objective signs of lung involvement * respiratory frequency ≥25/min, blood oxygen saturation (sao2) \< 95% in a-a, pao2/fio2 ratio \< 300 * hospital admission since less than 48 hours * signature of informed consent for study participation

inclusion criteria: - age > 18 years - diagnosis of pneumonia caused by covid-19 - respiratory and/or systemic symptoms and initial mild respiratory failure and with objective signs of lung involvement - respiratory frequency ≥25/min, blood oxygen saturation (sao2) < 95% in a-a, pao2/fio2 ratio < 300 - hospital admission since less than 48 hours - signature of informed consent for study participation

inclusion criteria: - age > 18 years - diagnosis of pneumonia caused by covid-19 - respiratory and/or systemic symptoms and initial mild respiratory failure and with objective signs of lung involvement - respiratory frequency ≥25/min, blood oxygen saturation (sao2) < 95% in a-a, pao2/fio2 ratio < 300 - hospital admission since less than 48 hours - signature of informed consent for study participation