inclusion criteria: - confirmed respiratory tract sars-cov-2 infection by at least one pcr on nasopharygeal sample or a bronchoalveolar lavage - patient hospitalized with clinical, biological and radiological features corresponding to the following stages : - stage 2b: hypoxic pneumonia (respiratory frequency > 30/mn, sa02 < 90 mmhg on room air) associated with a clear biological inflammatory syndrome (crp > 150 mg/l) - stage 3: ards defined by a patient under mechanical ventilation with a ratio pao2/fio2 < 300 for more than 24h - evolved stage 3: ards according to previous definition associated with another organ failure or syndrome among: - a state of shock with noradrenaline dosing > 3mg/h - acute kidney failure oligo-anuric or justifying extra-renal purification - hepatocellular insufficiency or coagulopathy with a v factor < 50% - myocarditis responsible for acute heart failure and or cardiogenic shock - hemophagocytic syndrome - hyperferritinemia > 5000 ng/ml - subject or legal representative having expressed written consent after information - subject affiliated to or entitled to a social security regimen - patient presenting in a life-threatening emergency situation that does not allow consent to be obtained

inclusion criteria: - confirmed respiratory tract sars-cov-2 infection by at least one pcr on nasopharygeal sample or a bronchoalveolar lavage - patient hospitalized with clinical, biological and radiological features corresponding to the following stages : - stage 2b: hypoxic pneumonia (respiratory frequency > 30/mn, sa02 < 90 mmhg on room air) associated with a clear biological inflammatory syndrome (crp > 150 mg/l) - stage 3: ards defined by a patient under mechanical ventilation with a ratio pao2/fio2 < 300 for more than 24h - evolved stage 3: ards according to previous definition associated with another organ failure or syndrome among: - a state of shock with noradrenaline dosing > 3mg/h - acute kidney failure oligo-anuric or justifying extra-renal purification - hepatocellular insufficiency or coagulopathy with a v factor < 50% - myocarditis responsible for acute heart failure and or cardiogenic shock - hemophagocytic syndrome - hyperferritinemia > 5000 ng/ml - subject or legal representative having expressed written consent after information - subject affiliated to or entitled to a social security regimen - patient presenting in a life-threatening emergency situation that does not allow consent to be obtained