There's allot of debate as to whether steroid therapy is actually best for lung infections BUT prednisone is an awesome anti-inflammatory. If your lung infections was mainly inflammation (possibly from acute exposure to asbestos) then I can totally see the prednisone clearing it up quickly. Unfortunately, like some NSAID's steroids do suppress the immune system too so they're usually avoided in clinical settings, but since doctors usually have their head's up their ass, it might help with Covid-19 too, especially the acute inflammation. I'd have to look into it further :)