The money quote is misleading, because they don’t actually have a mechanistic model. They’re just fitting a parameterized logistic curve to all the death data in the world. They incorporate some black-box factor that causes more deaths without social distancing, and arbitrarily declare that factor’s effect is 66%/33%/0 with 1/2/3+ social distancing measures. The goal isn’t to claim that nobody’s ever infected in the 0 case, just that the not-social-distancing factor is gone, so our course should follow the empirical progression of countries that do social distancing.
From a quick skim of the paper it looks like they effectively assume that implementing any 3 of those social distancing measures at the same time that Wuhan implemented their lockdown would lead to the same number of total deaths (with some adjustments).
This is less aggressive than assuming no new deaths after lockdown, but does seem quite optimistic given that the lockdown in Wuhan seems (much) more severe than school closures + travel restrictions + non-essential business closures. And this part of the model seems to be assumed rather than fit to data.
The money quote is misleading, because they don’t actually have a mechanistic model. They’re just fitting a parameterized logistic curve to all the death data in the world. They incorporate some black-box factor that causes more deaths without social distancing, and arbitrarily declare that factor’s effect is 66%/33%/0 with 1/2/3+ social distancing measures. The goal isn’t to claim that nobody’s ever infected in the 0 case, just that the not-social-distancing factor is gone, so our course should follow the empirical progression of countries that do social distancing.
From a quick skim of the paper it looks like they effectively assume that implementing any 3 of those social distancing measures at the same time that Wuhan implemented their lockdown would lead to the same number of total deaths (with some adjustments).
This is less aggressive than assuming no new deaths after lockdown, but does seem quite optimistic given that the lockdown in Wuhan seems (much) more severe than school closures + travel restrictions + non-essential business closures. And this part of the model seems to be assumed rather than fit to data.