[philipn]

I think the table in that paper is just confusing. The parenthesized numbers are for portion of the total number of people, rather than the portion of that category.

For instance, there are 137 current smokers. 108 are listed as non-severe. 29 are listed as severe. This means 108/137 = 79% non-severe, 29/137 21% severe.

Never smoked: 927 total, 793/927 non-severe (86%), 134/927 severe (14%).

Hope that makes sense. That table confused me too. Don't start smoking!

[Alex3917]

For context, around 60% of men in China smoke. Your proximate interpretation of the numbers is correct, but I think the real question is where are there so few smokers in the data. (And whether smoking confers some sort of protective effect by upregulating ACE2 receptors.)