Wrong again! Someone should tell E.W.: https://mathworld.wolfram.com/Kermack-McKendrickModel.html The logic may be different, but I think the argument for region variables is strong. Without region variables, it isn’t even clear how to choose maximum population size, and “the whole city” or “the whole country” seems to assume too much unity. If a person moves to a place with fewer social distancing measures, R0 should be higher. —Brad On Fri, May 22, 2020 at 10:31 AM Michael Kleber <michael.kleber@gmail.com> wrote:
Just for clarity of terminology: The epidemiological definition of R0 is the average reproduction number *in a completely susceptible population*. Things which decrease the fraction of the population that are susceptible to infection (like immunity of recovered people, or like nonzero vaccination rates) affect what people-being-careful call R_e or R_eff, the *effective* reproduction number.
Obviously not everyone is careful enough to use the terms like trained epidemiologists wish they would :-)
--Michael
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