If you expect your calculations to yield an absolute mortality value for a given bug, yes.
If you are only hoping to compare the mortality of a given plague to historical plagues, using the same methodologies give a good estimate of relative deadliness.
Except that assumes that the same percentage of cases rises to the level requiring attention. Maybe Corona is incredibly weak but incredibly wide spread. Maybe the opposite.
But I get what you're saying. In the end we can only guess wisely w/in a likely range.
Another concern with this puppy is ability to re-infect (I think medium-low) and any long term damage, even if slight (why you might want to avoid it even if you're not in the age death-zone)
Since I don't stick my finger in holes in fences when I can't determine if there is a hungry rottweiler on the other side, I will be calmly doing 100% of what I can do to avoid this short of going crazy. Got to get sun, exercise and a little human interaction. Too LITTLE of life itself depresses the immune system.