A toy model that makes some sense to me is that the two population distinction is (close to) literally true; that there’s a subset of like 20% of people who have reduced their risk by 95%+, and models should really be considering only the other 80% of the population, which is much more homogeneous.
Then because you started with effectively 20% population immunity, that means R0 is actually substantially higher, and each additional piece of immunity is less significant because of that.
I haven’t actually computed anything with this model so I don’t know whether it is actually explanatory.
A toy model that makes some sense to me is that the two population distinction is (close to) literally true; that there’s a subset of like 20% of people who have reduced their risk by 95%+, and models should really be considering only the other 80% of the population, which is much more homogeneous.
Then because you started with effectively 20% population immunity, that means R0 is actually substantially higher, and each additional piece of immunity is less significant because of that.
I haven’t actually computed anything with this model so I don’t know whether it is actually explanatory.