[Retric]

2.5% growth rate is slow when the population is young, space and food is abundant, and birth control is non existent.

European recovery was faster and much more complex than that after the Black Death. Europe’s population was 78.7 million in 1300, 70.7 million in 1350, and back to 78.1 million in 1400. https://en.wikipedia.org/wiki/Medieval_demography A closer look into the numbers shows 80% recovery was quite fast even in areas that where devastated, but after that wars etc knocked the population back down.

It’s the classic S curve where growth is exponential up to carrying capacity and slows as you approach it.

As to immunity, I am referring to individual immunity from exposure and survival not genetic immunity. Europe never became immune to smallpox, but by exposing people young they are much more capable of fighting off infections. COVID deaths for people 35-44 are 10x that of people aged 5-14. We don’t think of 35-44 year olds as a high risk group because it just keeps getting dramatically worse as people age. 45-54 year olds are more than twice as likely to die as people 10 years younger. It more than doubles again 55-64, and by 65+ your in the high risk groups.