Recovered infected people for plasma donations.

With 330 million people in the US there are probably thousands who have never have been infected by COVID-19 but due to a “happy accident” in a prior infection of another disease have antibodies that work against COVID-19, we just do not know who they are....

I got sick in China in 1981 and have also gone through many caves with bats in them in KY, NC, AK and VA.

Since you can get sick and have no symptoms, who knows what antibodies might be in my blood?

Bats have suffered from humans bringing “Novel” diseases into their caves.
Millions of bats have died from “White Nose Disease.”