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

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