Study of Abatacept in the Treatment of Hospitalized COVID-19 Participants With Respiratory Compromise

Adjusted mean change from baseline based on the following Ordinal 8-point Clinical Status Scale that was proposed for the National Institute of Allergy and Infectious Diseases (NIAID) Adaptive COVID-19 Treatment Trial (ACTT) and is recorded by the worst score (lowest number) state for each day:

1. Death;
2. Hospitalized, on invasive mechanical ventilation or extracorporeal membrane oxygenation (ECMO);
3. Hospitalized, on non-invasive mechanical ventilation or high-flow oxygen devices;
4. Hospitalized, requiring supplemental oxygen;
5. Hospitalized, not requiring supplemental oxygen - requiring ongoing medical care (COVID-19 related or otherwise);
6. Hospitalized, not requiring supplemental oxygen - no longer requires ongoing medical care;
7. Not hospitalized, limitation on activities and/or requiring home oxygen;
8. Not hospitalized, no limitation on activities Baseline is defined as the last assessment done prior or on Day 1

Percentage of participants who died due to any cause. Participants in the following Ordinal 8-point Clinical Status Scale that is recorded by the worst score (lowest number) state for each day meet this definition:

1) Death

Respiratory failure is defined by the type of resources required as defined by the use of any of these: Mechanical ventilation, extracorporeal membrane oxygenation (ECMO) or oxygen delivery by noninvasive positive pressure or high flow nasal cannula.

Participants in the following Ordinal 8-point Clinical Status Scale that is recorded by the worst score (lowest number) state for each day meet this definition:

4) Hospitalized, requiring supplemental oxygen; 5) Hospitalized, not requiring supplemental oxygen - requiring ongoing medical care (COVID-19 related or otherwise); 6) Hospitalized, not requiring supplemental oxygen - no longer requires ongoing medical care; 7) Not hospitalized, limitation on activities and/or requiring home oxygen; 8) Not hospitalized, no limitation on activities

Recovery of pulmonary function is assessed by the percentage of participants returned to room air on day 28 after they were oxygen dependent and dependence on oxygen has been noted to be prolonged even after hospital discharge.

Participants in the following Ordinal 8-point Clinical Status Scale that is recorded by the worst score (lowest number) state for each day meet this definition:

5) Hospitalized, not requiring supplemental oxygen - requiring ongoing medical care (COVID-19 related or otherwise); 6) Hospitalized, not requiring supplemental oxygen - no longer requires ongoing medical care; 8) Not hospitalized, no limitation on activities

Percentage of participants alive and discharged from the hospital on day 28. Participants in the following Ordinal 8-point Clinical Status Scale that is recorded by the worst score (lowest number) state for each day meet this definition:

7) Not hospitalized, limitation on activities and/or requiring home oxygen; 8) Not hospitalized, no limitation on activities

Percentage of participants with serious adverse events (SAEs). SAE is defined as any untoward medical occurrence that, at any dose:

• Results in death
• Is life threatening
• Requires inpatient hospitalization
• Results in persistent or significant disability
• Is a congenital anomaly/birth defect
• Is an important medical event