My wife works in healthcare and caught some random respiratory illness in December 2019 that lingered on for 3 weeks. Her o2 levels the entire time was hanging around 94-96% so eventually we went to see her PCP. He found "adventitious" sounds in her lungs via stethoscope and prescribed her some steroids. It had an immediate effect and I thank god everyday she was diagnosed and treated before MSM made covid the black plague.