Earlier quoted context omitted.
Can you provide some evidence that this happened now, or for earlier diseases? Manaus in Brazil doesn't count, FTR. It never ever reached herd immunity: the data was a large overestimation.
I think my evidence is that there are variants. Isn't the way variants work: - A human gets infected - The human becomes a virus factory - While producing gazillions of viruses, mutations occur - Mutations are variants
(From memory, don’t have a link handy)