Execpt herd immunity doesn't apply to viruses that mutate heavily and where the immunity isn't durable. Dr. Anthony Fauci previously believed that herd immunity could be achieved with COVID, but he has since changed his mind:
So, with regard to that issue and something you mentioned earlier, how should we define herd immunity with respect to COVID, I mean, how do we think of it?
I wrote a paper on that. It was a simple paper [9]. It stated that we cannot apply the standard criteria of herd immunity. It's not applicable with SARS-CoV-2. And the reason is, it's simple. I can synopsize the paper in 30 seconds. One is that herd immunity is dependent on an immune response that is durable, measured in decades to a lifetime, and a pathogen that does not change. So, you have clear-cut herd immunity with measles. Why? The measles that I got infected with as a child, because I was born before the measles vaccine, is the same measles that's killing kids in the developing world today.
Number 2, if you get infected with measles or you get vaccinated with measles, the duration of protection minimally is decades and maximally is lifetime. Those are the criteria that you need for herd immunity. Because if you have a pathogen that keeps changing like the multiple variants of SARS, and if you have a duration of immunity that's measured in months, the entire concept of herd immunity is no longer valid. That's the point.
Excatly. Sopuli has become the instance for all things Finland, so that community would be more than welcome!