inclusion criteria * hospitalized * covid-19 pneumonia confirmed by a positive polymerase chain reaction (pcr) of any specimen and radiographic imaging * spo2 \< 94% while on ambient air inclusion criteria specific to long-term extension * participated in study ml42528 (empacta) (includes participants who completed or discontinued early from the main study) exclusion criteria * known severe allergic reactions to tcz or other monoclonal antibodies * require continuous positive airway pressure (cpap), bilevel positive airway pressure (bipap), or invasive mechanical ventilation * 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 * immunocompromised (besides well-controlled hiv) or on immunosuppressive therapy (except for steroids for covid), advanced cancer * have received oral anti-rejection or immunomodulatory drugs (including tcz) within the past 3 months * participating in another interleukin (il)-6 antagonist clinical trial or other drug clinical trials (participation in covid-19 anti-viral trials may be permitted if approved by medical monitor) * alanine aminotransferase (alt) or aspartate aminotransferase (ast) \> 10 x upper limit of normal (uln) detected within 24 hours at screening (according to local laboratory reference ranges) * absolute neutrophil count (anc) \< 1000/ul at screening (according to local laboratory reference ranges) * platelet count \< 50,000/ul at screening (according to local laboratory reference ranges) * pregnant or breastfeeding, or positive pregnancy test in a pre-dose examination * treatment with an investigational drug within 5 half lives or 30 days (whichever is longer) of randomization (investigational covid-19 antivirals may be permitted if approved by medical monitor) * 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 * any history of diverticulitis or gi perforation * use of systemic corticosteroids unless on a stable chronic dose

inclusion criteria * hospitalized * covid-19 pneumonia confirmed by a positive polymerase chain reaction (pcr) of any specimen and radiographic imaging * spo2 \< 94% while on ambient air inclusion criteria specific to long-term extension * participated in study ml42528 (empacta) (includes participants who completed or discontinued early from the main study) exclusion criteria * known severe allergic reactions to tcz or other monoclonal antibodies * require continuous positive airway pressure (cpap), bilevel positive airway pressure (bipap), or invasive mechanical ventilation * 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 * immunocompromised (besides well-controlled hiv) or on immunosuppressive therapy (except for steroids for covid), advanced cancer * have received oral anti-rejection or immunomodulatory drugs (including tcz) within the past 3 months * participating in another interleukin (il)-6 antagonist clinical trial or other drug clinical trials (participation in covid-19 anti-viral trials may be permitted if approved by medical monitor) * alanine aminotransferase (alt) or aspartate aminotransferase (ast) \> 10 x upper limit of normal (uln) detected within 24 hours at screening (according to local laboratory reference ranges) * absolute neutrophil count (anc) \< 1000/ul at screening (according to local laboratory reference ranges) * platelet count \< 50,000/ul at screening (according to local laboratory reference ranges) * pregnant or breastfeeding, or positive pregnancy test in a pre-dose examination * treatment with an investigational drug within 5 half lives or 30 days (whichever is longer) of randomization (investigational covid-19 antivirals may be permitted if approved by medical monitor) * 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 * any history of diverticulitis or gi perforation * use of systemic corticosteroids unless on a stable chronic dose

inclusion criteria - hospitalized - covid-19 pneumonia confirmed by a positive polymerase chain reaction (pcr) of any specimen and radiographic imaging - spo2 < 94% while on ambient air inclusion criteria specific to long-term extension - participated in study ml42528 (empacta) (includes participants who completed or discontinued early from the main study) exclusion criteria - known severe allergic reactions to tcz or other monoclonal antibodies - require continuous positive airway pressure (cpap), bilevel positive airway pressure (bipap), or invasive mechanical ventilation - 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 - immunocompromised (besides well-controlled hiv) or on immunosuppressive therapy (except for steroids for covid), advanced cancer - have received oral anti-rejection or immunomodulatory drugs (including tcz) within the past 3 months - participating in another interleukin (il)-6 antagonist clinical trial or other drug clinical trials (participation in covid-19 anti-viral trials may be permitted if approved by medical monitor) - alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 10 x upper limit of normal (uln) detected within 24 hours at screening (according to local laboratory reference ranges) - absolute neutrophil count (anc) < 1000/ul at screening (according to local laboratory reference ranges) - platelet count < 50,000/ul at screening (according to local laboratory reference ranges) - pregnant or breastfeeding, or positive pregnancy test in a pre-dose examination - treatment with an investigational drug within 5 half lives or 30 days (whichever is longer) of randomization (investigational covid-19 antivirals may be permitted if approved by medical monitor) - 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 - any history of diverticulitis or gi perforation - use of systemic corticosteroids unless on a stable chronic dose

inclusion criteria - hospitalized - covid-19 pneumonia confirmed by a positive polymerase chain reaction (pcr) of any specimen and radiographic imaging - spo2 < 94% while on ambient air inclusion criteria specific to long-term extension - participated in study ml42528 (empacta) (includes participants who completed or discontinued early from the main study) exclusion criteria - known severe allergic reactions to tcz or other monoclonal antibodies - require continuous positive airway pressure (cpap), bilevel positive airway pressure (bipap), or invasive mechanical ventilation - 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 - immunocompromised (besides well-controlled hiv) or on immunosuppressive therapy (except for steroids for covid), advanced cancer - have received oral anti-rejection or immunomodulatory drugs (including tcz) within the past 3 months - participating in another interleukin (il)-6 antagonist clinical trial or other drug clinical trials (participation in covid-19 anti-viral trials may be permitted if approved by medical monitor) - alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 10 x upper limit of normal (uln) detected within 24 hours at screening (according to local laboratory reference ranges) - absolute neutrophil count (anc) < 1000/ul at screening (according to local laboratory reference ranges) - platelet count < 50,000/ul at screening (according to local laboratory reference ranges) - pregnant or breastfeeding, or positive pregnancy test in a pre-dose examination - treatment with an investigational drug within 5 half lives or 30 days (whichever is longer) of randomization (investigational covid-19 antivirals may be permitted if approved by medical monitor) - 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 - any history of diverticulitis or gi perforation - use of systemic corticosteroids unless on a stable chronic dose

inclusion criteria - hospitalized - covid-19 pneumonia confirmed by a positive polymerase chain reaction (pcr) of any specimen and radiographic imaging - spo2 < 94% while on ambient air exclusion criteria - known severe allergic reactions to tcz or other monoclonal antibodies - require continuous positive airway pressure (cpap), bilevel positive airway pressure (bipap), or invasive mechanical ventilation - 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 - immunocompromised (besides well-controlled hiv) or on immunosuppressive therapy (except for steroids for covid), advanced cancer - have received oral anti-rejection or immunomodulatory drugs (including tcz) within the past 3 months - participating in another interleukin (il)-6 antagonist clinical trial or other drug clinical trials (participation in covid-19 anti-viral trials may be permitted if approved by medical monitor) - alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 10 x upper limit of normal (uln) detected within 24 hours at screening (according to local laboratory reference ranges) - absolute neutrophil count (anc) < 1000/ul at screening (according to local laboratory reference ranges) - platelet count < 50,000/ul at screening (according to local laboratory reference ranges) - pregnant or breastfeeding, or positive pregnancy test in a pre-dose examination - treatment with an investigational drug within 5 half lives or 30 days (whichever is longer) of randomization (investigational covid-19 antivirals may be permitted if approved by medical monitor) - 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 - any history of diverticulitis or gi perforation - use of systemic corticosteroids unless on a stable chronic dose

inclusion criteria - hospitalized - covid-19 pneumonia confirmed by a positive polymerase chain reaction (pcr) of any specimen and radiographic imaging - spo2 < 94% while on ambient air exclusion criteria - known severe allergic reactions to tcz or other monoclonal antibodies - require continuous positive airway pressure (cpap), bilevel positive airway pressure (bipap), or invasive mechanical ventilation - 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 - immunocompromised (besides well-controlled hiv) or on immunosuppressive therapy (except for steroids for covid), advanced cancer - have received oral anti-rejection or immunomodulatory drugs (including tcz) within the past 3 months - participating in another interleukin (il)-6 antagonist clinical trial or other drug clinical trials (participation in covid-19 anti-viral trials may be permitted if approved by medical monitor) - alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 10 x upper limit of normal (uln) detected within 24 hours at screening (according to local laboratory reference ranges) - absolute neutrophil count (anc) < 1000/ul at screening (according to local laboratory reference ranges) - platelet count < 50,000/ul at screening (according to local laboratory reference ranges) - pregnant or breastfeeding, or positive pregnancy test in a pre-dose examination - treatment with an investigational drug within 5 half lives or 30 days (whichever is longer) of randomization (investigational covid-19 antivirals may be permitted if approved by medical monitor) - 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 - any history of diverticulitis or gi perforation - use of systemic corticosteroids unless on a stable chronic dose