inclusion criteria: * signature and agreement to the free consent form; * both sexes, of any ethnic origin, aged between 18 and 90 years; * covid-19 infected patients diagnosed by rt-pcr (reverse-transcriptase polymerase chain reaction) or with a strong suspicion of covid-19 by clinical evaluation through compatible clinical and radiological findings; * time of disease evolution less than 10 days; * radiological diagnosis of grade 2a pneumonia, with gas exchange ratio \> 200 on blood gas analysis (pao2 / pfio2), characterizing mild hypoxemia; * indication of hospital treatment regime, provided that the period of hospitalization before inclusion is not more than 24 hours; * need for supplemental oxygen therapy (o2) less than 5l / min.

inclusion criteria: * signature and agreement to the free consent form; * both sexes, of any ethnic origin, aged between 18 and 90 years; * covid-19 infected patients diagnosed by rt-pcr (reverse-transcriptase polymerase chain reaction) or with a strong suspicion of covid-19 by clinical evaluation through compatible clinical and radiological findings; * time of disease evolution less than 10 days; * radiological diagnosis of grade 2a pneumonia, with gas exchange ratio \> 200 on blood gas analysis (pao2 / pfio2), characterizing mild hypoxemia; * indication of hospital treatment regime, provided that the period of hospitalization before inclusion is not more than 24 hours; * need for supplemental oxygen therapy (o2) less than 5l / min.

inclusion criteria: - signature and agreement to the free consent form; - both sexes, of any ethnic origin, aged between 18 and 90 years; - covid-19 infected patients diagnosed by rt-pcr (reverse-transcriptase polymerase chain reaction) or with a strong suspicion of covid-19 by clinical evaluation through compatible clinical and radiological findings; - time of disease evolution less than 10 days; - radiological diagnosis of grade 2a pneumonia, with gas exchange ratio > 200 on blood gas analysis (pao2 / pfio2), characterizing mild hypoxemia; - indication of hospital treatment regime, provided that the period of hospitalization before inclusion is not more than 24 hours; - need for supplemental oxygen therapy (o2) less than 5l / min.

inclusion criteria: - signature and agreement to the free consent form; - both sexes, of any ethnic origin, aged between 18 and 90 years; - covid-19 infected patients diagnosed by rt-pcr (reverse-transcriptase polymerase chain reaction) or with a strong suspicion of covid-19 by clinical evaluation through compatible clinical and radiological findings; - time of disease evolution less than 10 days; - radiological diagnosis of grade 2a pneumonia, with gas exchange ratio > 200 on blood gas analysis (pao2 / pfio2), characterizing mild hypoxemia; - indication of hospital treatment regime, provided that the period of hospitalization before inclusion is not more than 24 hours; - need for supplemental oxygen therapy (o2) less than 5l / min.