I think you have it. The fats don't get to live until a ripe old age when one's immune system is weakened by default, so really the measure you should go by is how many of the hospitalizations of under 80s (or maybe 70s/60s?) are for fatties versus the spread of it in that general population, i.e. for under 60s, 7/10 of obese patients who contracted COVID are hospitalized, versus 2/10 of normal weight patients.