Coronavirus death rate falling in hospitals
bbc.com
bbc.com
https://www.reuters.com/article/us-health-coronavirus-italy-...
Also the studies about Vitamin D. Doesn’t hurt to increase the intake, especially for those chronically low. Many of those folks are in high risk groups.
Less concern about surfaces and more focus on avoiding stale air.
So many learnings came from the field.
At this point there’s a definite effect but the cause(s) are only speculative.