inclusion criteria: * age\> 18 years * diagnosis of covid 19, confirmed by rt-pcr on a nasopharyngeal swab * covid 19 pneumonia with the following clinical characteristics: spo2 in ambient air \<93% and alveolar pressure of oxygen / inspiratory fraction of oxygen (pao2 / fio2 - p / f \<300 mmhg. * lymphocytopenia defined as lymphocytes \<1500 / mcl or \<20% of white blood cells

inclusion criteria: * age\> 18 years * diagnosis of covid 19, confirmed by rt-pcr on a nasopharyngeal swab * covid 19 pneumonia with the following clinical characteristics: spo2 in ambient air \<93% and alveolar pressure of oxygen / inspiratory fraction of oxygen (pao2 / fio2 - p / f \<300 mmhg. * lymphocytopenia defined as lymphocytes \<1500 / mcl or \<20% of white blood cells

inclusion criteria: - age> 18 years - diagnosis of covid 19, confirmed by rt-pcr on a nasopharyngeal swab - covid 19 pneumonia with the following clinical characteristics: spo2 in ambient air <93% and alveolar pressure of oxygen / inspiratory fraction of oxygen (pao2 / fio2 - p / f <300 mmhg. - lymphocytopenia defined as lymphocytes <1500 / mcl or <20% of white blood cells

inclusion criteria: - age> 18 years - diagnosis of covid 19, confirmed by rt-pcr on a nasopharyngeal swab - covid 19 pneumonia with the following clinical characteristics: spo2 in ambient air <93% and alveolar pressure of oxygen / inspiratory fraction of oxygen (pao2 / fio2 - p / f <300 mmhg. - lymphocytopenia defined as lymphocytes <1500 / mcl or <20% of white blood cells