Inclusion Criteria:  Men and women aged 21-80, Primary ICU patients (admitted to the hospital, transfer from another hospital or department less than 72 hours), Positive PCR test for SARS-CoV-2, PaO2 / FiO2 <300, SOFA ≥ 4 with clinic of organ dysfunction.  Exclusion Criteria:  Pregnancy, The presence of signs of a bacterial infection or the addition of secondary purulent-septic complications, Cancer (including blood diseases), Chronic diseases in the stage of decompensation, Recent or ongoing bleeding, Syndrome of disseminated intravascular coagulation, Thrombocytopenia, Patients in terminal condition or receiving palliative care, Patients for whom, for any reason, the use of anticoagulants is not safe.