[SiVal]

As I said, test for antibodies. Put the "who's more likely to work at Walmart" speculations aside and start with, "Of the people who were provably infected, how likely were they to die?" question. If there are large differences, then look at age (for sure), prior health factors, gender, ethnicity, etc., to see what (if anything) made the virus not matter, and consider whether there might be other ways (besides vaccination) to make future viruses (prob some category) not matter to anyone.