inclusion criteria (donors): - signed informed consent - at least positive for 1 q-pcr test for sars-cov-2 - 14 days of covid-19 clinical remission - positive serologic test for sars-cov-2 - requirements to donate according to nom-253-ssa1-2012 - to accept sample storing for future study inclusion criteria (receptors): - signed informed consent provided by the patient, legal guardian or the health provider if not available - patients hospitalized in an icu dedicated to the treatment of covid-19 patients - at least positive for 1 q-pcr test for sars-cov-2 - patients with covid-19 defined as severe or critically ill: severe: rf > 30 bpm, oxygen saturation <94%, pa/fio2 <301, bilateral lung infiltrates that extends in >50% (by chest radiograph or ct scan) in 24-48 hours critically ill: respiratory failure (pao2 <60 mmhg or sato2 <90% with fio2 >60%) and septic shock (map <65 mmhg with vasoactive requirement, lactate > 2 mmol/l and sofa score >1)

inclusion criteria (donors): - signed informed consent - at least positive for 1 q-pcr test for sars-cov-2 - 14 days of covid-19 clinical remission - positive serologic test for sars-cov-2 - requirements to donate according to nom-253-ssa1-2012 - to accept sample storing for future study inclusion criteria (receptors): - signed informed consent provided by the patient, legal guardian or the health provider if not available - patients hospitalized in an icu dedicated to the treatment of covid-19 patients - at least positive for 1 q-pcr test for sars-cov-2 - patients with covid-19 defined as severe or critically ill: severe: rf > 30 bpm, oxygen saturation <94%, pa/fio2 <301, bilateral lung infiltrates that extends in >50% (by chest radiograph or ct scan) in 24-48 hours critically ill: respiratory failure (pao2 <60 mmhg or sato2 <90% with fio2 >60%) and septic shock (map <65 mmhg with vasoactive requirement, lactate > 2 mmol/l and sofa score >1)