* inclusion criteria: * age 18-80 years. * severe pneumonia covid-19 defined as: * nasopharyngeal smear with rcp positive for sars-cov-2 * x-rays (or other technique) pulmonary infiltrates compatible with pneumonia. * 1 or more of the following criteria: * ambient air oxygen saturation \<= 94% measured with a pulse oximeter. * pa:fio2 (partial pressure o2/fraction of inspired o2) \<=300. * sa:fio2 (o2 saturation measured with pulse oximeter/ fraction of inspired o2) \<=350. * high suspicion of css that could resemble mas-like: represented by il-6 values \> 40 pg/ml and/or ferritin \>500 ug/l and/or pcr \> 30 mg/l (rationale: ≥ 5 upper normal limit) and/or ldh \>300 ui/l. we have chosen these parameters because they are implemented in all the participating hospitals, they are a reflection of the cytokine storm and they have also been significant in terms of predicting mortality in patients with covid-19 (9). * written informed consent. the protocol will be explained to the patient in front of a nurse who will act as a legal witness by signing the document on behalf of the patient. *

* inclusion criteria: * age 18-80 years. * severe pneumonia covid-19 defined as: * nasopharyngeal smear with rcp positive for sars-cov-2 * x-rays (or other technique) pulmonary infiltrates compatible with pneumonia. * 1 or more of the following criteria: * ambient air oxygen saturation \<= 94% measured with a pulse oximeter. * pa:fio2 (partial pressure o2/fraction of inspired o2) \<=300. * sa:fio2 (o2 saturation measured with pulse oximeter/ fraction of inspired o2) \<=350. * high suspicion of css that could resemble mas-like: represented by il-6 values \> 40 pg/ml and/or ferritin \>500 ug/l and/or pcr \> 30 mg/l (rationale: ≥ 5 upper normal limit) and/or ldh \>300 ui/l. we have chosen these parameters because they are implemented in all the participating hospitals, they are a reflection of the cytokine storm and they have also been significant in terms of predicting mortality in patients with covid-19 (9). * written informed consent. the protocol will be explained to the patient in front of a nurse who will act as a legal witness by signing the document on behalf of the patient. *

- inclusion criteria: - age 18-80 years. - severe pneumonia covid-19 defined as: - nasopharyngeal smear with rcp positive for sars-cov-2 - x-rays (or other technique) pulmonary infiltrates compatible with pneumonia. - 1 or more of the following criteria: - ambient air oxygen saturation <= 94% measured with a pulse oximeter. - pa:fio2 (partial pressure o2/fraction of inspired o2) <=300. - sa:fio2 (o2 saturation measured with pulse oximeter/ fraction of inspired o2) <=350. - high suspicion of css that could resemble mas-like: represented by il-6 values > 40 pg/ml and/or ferritin >500 ug/l and/or pcr > 30 mg/l (rationale: ≥ 5 upper normal limit) and/or ldh >300 ui/l. we have chosen these parameters because they are implemented in all the participating hospitals, they are a reflection of the cytokine storm and they have also been significant in terms of predicting mortality in patients with covid-19 (9). - written informed consent. the protocol will be explained to the patient in front of a nurse who will act as a legal witness by signing the document on behalf of the patient. -

- inclusion criteria: - age 18-80 years. - severe pneumonia covid-19 defined as: - nasopharyngeal smear with rcp positive for sars-cov-2 - x-rays (or other technique) pulmonary infiltrates compatible with pneumonia. - 1 or more of the following criteria: - ambient air oxygen saturation <= 94% measured with a pulse oximeter. - pa:fio2 (partial pressure o2/fraction of inspired o2) <=300. - sa:fio2 (o2 saturation measured with pulse oximeter/ fraction of inspired o2) <=350. - high suspicion of css that could resemble mas-like: represented by il-6 values > 40 pg/ml and/or ferritin >500 ug/l and/or pcr > 30 mg/l (rationale: ≥ 5 upper normal limit) and/or ldh >300 ui/l. we have chosen these parameters because they are implemented in all the participating hospitals, they are a reflection of the cytokine storm and they have also been significant in terms of predicting mortality in patients with covid-19 (9). - written informed consent. the protocol will be explained to the patient in front of a nurse who will act as a legal witness by signing the document on behalf of the patient. -