You wrote Around 45% of Americans have conditions that would make the coronavirus very dangerous, such as diabetes, obesity, or simply being older.

Where is the evidence for “simply being older?” A very small percentage of “older” people live in nursing homes, yet nursing homes account for 1/3 of coronavirus deaths in the US. I haven’t seen any data that separates the effects of age from the effects of being in a nursing home. Eric Driscoll’s comment makes a similar point.

Go to this link https://www.worldometers.info/coronavirus/coronavirus-age-sex-demographics/

and look at the column “without underlying conditions.” Age effects disappear.