I don’t think we can have much confidence in the

I don’t think we can have much confidence in the numerator or denominator right now. The numerator may be understated not only because we don’t know how many of those infected will ultimately recover, as you note. But also, we don’t know how many deaths have occurred that were because of coronavirus (COVID-19) but not attributed to it but some other cause.

The Diamond Princess data is not very useful because the population is so skewed to older individuals. It really is just the world’s largest floating petri dish.

From what we “know” now, it appears that SARS-CoV-2 is 10- 20-times worse than influenza, as far as mortality. And, SARS-CoV-2 appears to be 10 times less lethal than the original SARS virus. The real problem with this virus is how contagious (R0) it is and that one is contagious before you even know you have the virus.