I mean "naturally", in the sense that it is a process mediated by the immune system. Even a vaccine-induced immune response is natural. But yes, my choice of w

I mean "naturally", in the sense that it is a process mediated by the immune system. Even a vaccine-induced immune response is natural. But yes, my choice of words is confusing there. The point I am making is that herd immunity is not eradication. People (like the OP) confuse the two concepts. You can have herd immunity in a population, and the pathogen will still circulate. Observing that a virus still infects people is not evidence that herd immunity to that virus has not been achieved.