Here in the UK, when people are very seriously ill with the virus, likely to die etc the last chance is to place them in an induced coma to assist control of breathing. If you get out of that alive you've done well.
My own survey, of colleagues I KNOW have had the virus, reveals that 100% of over 55s have been placed into a coma, and thus been fortunate to live. In my survey I am ignoring government stats and using MY OWN EVIDENCE WHICH IS REAL, NOT THE FAKE NEWS FROM THE FAKE MEDIA.
I hope that's clearer. It's a while since I've done maths (according to my MSc Maths stepson I never have done mathematics, just arithmetic) but when I did probability it was quite acceptable to have a probability of 1.
Things may have changed. I guess they do!