* contraindications or unwilling to use steroids by patient or provider * refractory septic shock defined as a requirement of norepinephrine dose or equivalent above \>0.1 microgram/kilogram/minute or 2 or more vasopressors * pre-admission chronic use of steroids or other immunosuppressive medications * adrenal insufficiency * comfort care * leukopenia \<1000/mm or neutropenia \<500/mm (except if attributable to pneumonia) and hiv positive with a cd4 count \<100 * recent or past history of bone marrow or solid organ transplantation * hospital admission in the previous 30 days * suspected flare of interstitial lung disease (infectious and non-infectious) * positive influenza testing or high suspicion for influenza for the covid-19 arm of the study: inclusion criteria: * patients admitted to hospital with covid-19 pneumonia (high suspicion or confirmed by positive sars cov-2 testing). * acute respiratory failure spo2/fio2 \< 315 (spo2\<90% on room air or \<97% on 2l nc).

* contraindications or unwilling to use steroids by patient or provider * refractory septic shock defined as a requirement of norepinephrine dose or equivalent above \>0.1 microgram/kilogram/minute or 2 or more vasopressors * pre-admission chronic use of steroids or other immunosuppressive medications * adrenal insufficiency * comfort care * leukopenia \<1000/mm or neutropenia \<500/mm (except if attributable to pneumonia) and hiv positive with a cd4 count \<100 * recent or past history of bone marrow or solid organ transplantation * hospital admission in the previous 30 days * suspected flare of interstitial lung disease (infectious and non-infectious) * positive influenza testing or high suspicion for influenza for the covid-19 arm of the study: inclusion criteria: * patients admitted to hospital with covid-19 pneumonia (high suspicion or confirmed by positive sars cov-2 testing). * acute respiratory failure spo2/fio2 \< 315 (spo2\<90% on room air or \<97% on 2l nc).

- contraindications or unwilling to use steroids by patient or provider - refractory septic shock defined as a requirement of norepinephrine dose or equivalent above >0.1 microgram/kilogram/minute or 2 or more vasopressors - pre-admission chronic use of steroids or other immunosuppressive medications - adrenal insufficiency - comfort care - leukopenia <1000/mm or neutropenia <500/mm (except if attributable to pneumonia) and hiv positive with a cd4 count <100 - recent or past history of bone marrow or solid organ transplantation - hospital admission in the previous 30 days - suspected flare of interstitial lung disease (infectious and non-infectious) - positive influenza testing or high suspicion for influenza for the covid-19 arm of the study: inclusion criteria: - patients admitted to hospital with covid-19 pneumonia (high suspicion or confirmed by positive sars cov-2 testing). - acute respiratory failure spo2/fio2 < 315 (spo2<90% on room air or <97% on 2l nc).

- contraindications or unwilling to use steroids by patient or provider - refractory septic shock defined as a requirement of norepinephrine dose or equivalent above >0.1 microgram/kilogram/minute or 2 or more vasopressors - pre-admission chronic use of steroids or other immunosuppressive medications - adrenal insufficiency - comfort care - leukopenia <1000/mm or neutropenia <500/mm (except if attributable to pneumonia) and hiv positive with a cd4 count <100 - recent or past history of bone marrow or solid organ transplantation - hospital admission in the previous 30 days - suspected flare of interstitial lung disease (infectious and non-infectious) - positive influenza testing or high suspicion for influenza for the covid-19 arm of the study: inclusion criteria: - patients admitted to hospital with covid-19 pneumonia (high suspicion or confirmed by positive sars cov-2 testing). - acute respiratory failure spo2/fio2 < 315 (spo2<90% on room air or <97% on 2l nc).

- pre-admission chronic use of steroids or other immunosuppressive medications - adrenal insufficiency - comfort care - leukopenia <1000/mm or neutropenia <500/mm (except if attributable to pneumonia) and hiv positive with a cd4 count <100 - recent or past history of bone marrow or solid organ transplantation - hospital admission in the previous 90 days - suspected flare of interstitial lung disease (infectious and non-infectious) for the covid-19 arm of the study: inclusion criteria: - patients admitted to hospital with covid-19 pneumonia (confirmed by positive sars cov-2 testing). - acute respiratory failure (sao2/fio2 < 315 or pao2/fio2 < 300). exclusion critieria: - same as pneumonia arm above.

- pre-admission chronic use of steroids or other immunosuppressive medications - adrenal insufficiency - comfort care - leukopenia <1000/mm or neutropenia <500/mm (except if attributable to pneumonia) and hiv positive with a cd4 count <100 - recent or past history of bone marrow or solid organ transplantation - hospital admission in the previous 90 days - suspected flare of interstitial lung disease (infectious and non-infectious) for the covid-19 arm of the study: inclusion criteria: - patients admitted to hospital with covid-19 pneumonia (confirmed by positive sars cov-2 testing). - acute respiratory failure (sao2/fio2 < 315 or pao2/fio2 < 300). exclusion critieria: - same as pneumonia arm above.