[watwut]

> can be thought of as the expected number of cases directly generated by one case in a population where all individuals are susceptible to infection

Yeah, and that is contextual number, determined by population behavior and other factors.

Yes, population immunity should not be on that list, but the population behavior, weatcher and what not are still influencing it a lot.

[timr]

Population immunity has to be on the list: if the population has some level of immunity, it affects the observed R0. And we can't really measure immunity, other than in very crude ways (i.e. antibody tests for specific epitopes), so we can't control for it.

This isn't a political statement of any sort.