Clinical Efficacy of Heparin and Tocilizumab in Patients With Severe COVID-19 Infection

Inclusion Criteria: * Age ≥ 18 years; * Informed consent form signed by the patient or guardian or by audio with the guardian; * Positive result for COVID-19 in PCR (polymerase chain reaction) in nasopharyngeal swab or tracheal secretion up to 10 days before the inclusion and radiological evidence of COVID-19, by chest radiography or chest computed tomography; * Need for ≥ 4 L of supplemental oxygen to maintain peripheral oxygen saturation equal to or greater than 93% or need for invasive mechanical ventilation. Exclusion Criteria: * Risk of bleeding: * Clinical: active bleeding, major surgery in the last 30 days, gastrointestinal bleeding within 30 days; * Laboratory: platelet count \<50,000, INR\> 2 or APTT\> 50s; * Known or suspected adverse reaction to UFH, including heparin-induced thrombocytopenia (TIH); * Adverse reaction or allergy to tocilizumab; * Use of any of the following treatments: UFH to treat a thrombotic event within 12 hours before inclusion; HPBM in therapeutic dose within 12 hours before inclusion; warfarin (if used 7 days before and if INR greater than 2; thrombolytic therapy within 3 days before; and use of glycoprotein IIb / IIIa inhibitors within the previous 7 days; * Pregnant or lactating; * Absolute indication of anticoagulation due to atrial fibrillation or diagnosed thromboembolic event; * Refusal by family members and / or patient; * Active tuberculosis; * Bacterial infection confirmed by culture; * Neutropenia (\<1000 neutrophils / mm3); * Use of another immunosuppressive therapy that is not a corticosteroid; * Septic shock.