Study to Evaluate the Safety and Efficacy of ATYR1923 (Efzofitimod) In Participants With Severe Pneumonia Related to COVID-19

TEAEs were defined as adverse events (AEs) with an onset following administration of the first dose of study drug. AEs were defined as any untoward medical occurrence in a participant administered study drug and that does not necessarily have a causal relationship with the study drug. Worsening of a pre-existing medical condition should have been considered an AE if there was either an increase in severity, frequency, or duration of the condition or an association with significantly worse outcomes. SAEs were defined as any AE that, in the view of either the Investigator or Sponsor, resulted in any of the following outcomes as fatal, life-threatening, required in-participant hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, a congenital anomaly/birth defect, an important medical event. A summary of all SAEs and Other AEs (nonserious) regardless of causality is located in 'Reported Adverse Events' Section.

Time to hospital discharge was based on Kaplan-Meier estimate and was calculated as: discharge date - study drug administration date. Participants who died during hospitalization were censored at death date. Participants who remained hospitalized at end of study (EOS) were censored at EOS visit.

Time to recovery was based on Kaplan-Meier estimate and was calculated as: date of first time with a WHO scale score ≤3 - study drug administration date or date of discharge from hospital - study drug administration date, whichever occurred first. In the case that a participant did not reach WHO scale score ≤3 criteria, the participant was censored at EOS visit.

The number of participants was the non-missing value at the visit, which was used as the denominator for percentage calculation.

Number of days with supplemental O2 was calculated as stop date of supplemental O2 - start date of supplemental oxygen +1, if supplemental O2 started after study drug administration; otherwise, number of days with supplemental O2 was calculated as stop date of supplemental O2 - date of study drug administration +1. If there were multiple periods of supplemental O2, total days were the sum of each period.

Number of days with fever was calculated as stop date of fever - start date of fever +1, if fever started after study drug administration; otherwise, number of days with fever was calculated as stop date of fever - date of study drug administration +1. If there were multiple periods of fever, total days was the sum of each period.

WHO ordinal scale rated the clinical improvement of the participants on a scale of 0-8, where 0=No clinical or virological evidence of infection, 1=No limitation of activities, 2=limitation of activities, 3=Hospitalized, no oxygen therapy, 4=Oxygen by mask or nasal prongs, 5=Non-invasive ventilation or high flow oxygen, 6=Intubation and mechanical ventilation, 7=Ventilation + additional organ support, 8=Death. Change from Baseline data were represented on a scale of -7 to 4, where -7=a better change from Baseline score and 4=a worse change from Baseline score. Change from Baseline was derived as: visit value - Baseline value.

Time to improvement was based on Kaplan-Meier estimate and was defined as the date of decrease in WHO scale compared to Baseline by at least 1 point - study drug administration date or date of discharge from hospital - study drug administration date, whichever occurred first. In the case that a participant did not reach an improvement, the participant was censored at end of study date.