Earlier quoted context omitted.
If you want to know fatality rates you need a controlled population. South Korea isn't that, its level of testing isn't even much higher than Switzerlands at this point. There are only two known populations in which everyone was forced to be tested and their movement was limited, which thus makes up a controlled study: the Diamond Princess and the town of Vo in Italy. In both cases the fatality rate is much less than…
The Diamond Princess’s population is also small, extremely poorly represents the general population, and happened in a setting unrepresentative of the rest of the world. Passenger age is just about the only factor that would drive the mortality and infection rates up, everything else lowers it. As a model the Diamond Princess should probably be treated more as the floor rather than anything representing the average.
What are these everything else’s? By far the best predictor of patient mortality has been age. What else is it about the Diamond Princess population that would come even close, even in sum, to the predictive power of their age?