• ii. Hospitalized with COVID-19 pneumonia, based on chest X-ray or CT scan AND iii. Evidence of hyperinflammation: IL-6>40pg/mL (if available) OR CRP >2 mg/dL OR ferritin >2000 ng/mL AND iv. One or more of the following: impending need for requiring invasive or non-invasive mechanical ventilation OR shock requiring vasopressor (without evidence of bacterial / fungal infection) OR need for extracorporeal membrane oxygenation (ECMO) OR severe, refractor ARDS (PaO2/FiO2<200 mmHg)

Known severe allergic reactions to tocilizumab or other monoclonal antibodies - Active tuberculosis infection based on history - Suspected active bacterial, fungal, viral, or other infection (besides COVID-19) - In the opinion of the investigator, progression to death is imminent and inevitable within the next 24 hours, irrespective of the provision of treatments - Have received oral anti-rejection or immunomodulatory drugs (including tocilizumab) with the past 6 months - Participating in other drug clinical trials (participation in COVID-19 trials allowed) - Self-reported pregnant or breastfeeding - Any serious medical condition or abnormality of clinical laboratory tests that, in the investigator's judgment, precludes the patient's safe participation in and completion of the study - Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) > 10 x upper limit of normal (ULN) detected within 24 hours at baseline - Absolute neutrophil count (ANC) < 1000/mL at baseline - Platelet count < 50,000/mL at baseline