The COVID-19 infection primarily manifests itself as a respiratory tract infection, although new evidence indicates that this disease has systemic involvement involving multiple systems including the cardiovascular, respiratory, gastrointestinal, neurological, hematopoietic and immune systems. Recent studies have shown that in its pathophysiology, inflammation and thrombogenesis predominate, especially in the severe forms of COVID-19. Thus, the investigators hypothesized that the use of heparin and tocilizumab could potencially reduce inflammation and thrombogenesis in patients with severe COVID-19 infection, improving patients outcomes and survival.

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.