It's been a while since anyone argued that we were near herd immunity with COVID. For almost a year it was very trendy among a small faction to insist that if we just let the virus spread, that would ultimately be good, because the younger and healthier people were pretty likely to survive.
That wasn't a serious argument, even then. There was no way to actually divide young from old, low-risk from high-risk, and have them live in separate universes. Not to mention that even if it were logistically possible to build what I understood them to be envisioning as new communities or facilities or "camps" for "high-risk" people ... it's not even possible to engage with this, sorry.
What is worthwhile is the concept of herd immunity. Which is a basic principle of infectious disease. Once enough people have immune protection after vaccination, the microbe will stop spreading because it was no more viable hosts. (The concept applies only to vaccine-induced immunity, by definition, for purposes of standardization, even in disease where infections confer comparable immune memories).
So, did COVID break the rule? Most people have had it. Where is our herd immunity? We were promised herd immunity.
The answer is that we are seeing the effect. But it's temporary and local. Right after a big surge in a community, you will see months of very little transmission. It's a communal effect that works just like herd immunity. Even those people without robust immune memory are essentially protected by the high levels of immunity in their community.
But as this virus mutates and immunity wanes, so does the collective effect. Nowhere in the textbooks does it say that herd immunity need be permanent. Nor is it necessarily global. Nor even found everywhere in a single state. Like most good things, herd immunity comes and goes. And the going is unfortunately much easier than the coming.
Back in 2020, I wrote about "A New Understanding of Herd Immunity" by comparing it to chaos theory. I think that was basically right.
