I was born in 1950. At that time there had been an outbreak of smallpox. I was only a few months old. The pediatrician told my mother my chance of surviving the disease would be very small. My mother and father,after much deliberation, elected to have me vaccinated. The vaccine did not take. (No scar was left.) The doctor felt I needed another dose and so I was vaccinated a second time. Still no scarring. He researched reasons why this would happen and discovered that one person in a thousand has a truly “natural immunity” that prevents them from ever getting the disease. Those persons CANNOT get smallpox. As proof, I was required to recieve a vaccination again when I visited Israel during the early 1970’s and had the same results.
The same can be said of survivors of the Black Death.
Black Death genome survive
A genetic trait.
You are indeed very fortunate.