You are speaking about the Delta-32 mutation, which affects (now) about ten percent of the population.
It yields white blood cells that have a variation of the membrane that make it impossible for yersina (or hiv) to infect them.
No doubt it was increased by the plague, but I doubt that was the only factor.
Seems to me that I’ve read reports somewhere that the native American populations were a very healthy looking lot compared the Europeans that first came to the new world.
However, much of the Indian populations of north central and south America —were simply wiped out by new diseases brought over by the Europeans. further the die off so preceded the Europeans that with rare exceptions like in Mexico during the 1530 and 1560’s the Europeans had no knowledge of what happened. and how really big the Indian populations of the Americas were before they were wiped out by disease.
That this complete wipe out never happened in any parts of Africa or Asia. apparently because these populations already had been exposed to European diseases.
I'm not certain whether that is the mutation I was speaking about. I seem to recall reading that there is a variant in one of the proteins within the MHC II complex which is enriched in populations with European ancestry (descendants of the black death survivors). This was published a few months or maybe a year or so ago. I tried to do a Google search, and found a more recent publication discussing a polymorphism within the TLR2 protein that is also associated with survivors of the black death, but I cannot access the article at home. I have access at work, but whether I'll remember to look at the article is questionable.
It really is not surprising that a pandemic would select for certain gene variants. Evolutionary forces are constantly shaping us.
Except for food poisoning, I have not been sick in years. I watched both husband and son sniffle, sneeze, and cough with something a couple months ago, but I did not get sick. I think my immune system must have a very long memory for every virus I've ever encountered.