In a study published in the Journal of the American Heart Association American, researchers estimate that, among the 906,849 total COVID-19 hospitalizations that had occurred in U.S. adults as of November 18, 2020:
30% (274,322) were attributable to obesity
26% (237,738) were attributable to high blood pressure
21% (185,678) were attributable to diabetes, and
12% (106,139) were attributable to heart failure.
The interesting thing to note here, of course, is that all these conditions have a very large component of being minimized by a healthy lifestyle.
You can’t do anything about your age, and you can’t do anything about your genes, but you can do a lot about these major risk factors.