In the Oxford PR (and perhaps also in the medarxiv pre print, I don’t remember and am on phone now), it said the reason for starting this trial was that people

In the Oxford PR (and perhaps also in the medarxiv pre print, I don’t remember and am on phone now), it said the reason for starting this trial was that people with asthma are significantly underrepresented among COViD19 patients (you would expect them to be on par or even over represented as they start from a worse breathing baseline). Also, dexamethasone, a systemic steroid, seems to have comparable effects; likely, they both reduce or stop the damage from overactive immune response, which is likely a big part of covid complications.