Can it be that smoking plays big part in this? As this also explains gender statistics.

An early preprint from the team of China’s leading expert Zhong Nanshan tagged smokers and non-smokers among the 1099 cases they analyzed. 85.4% supposedly never smoked, with 14.5% of those cases severe. So it’s not like non-smokers are very much immune.

https://www.medrxiv.org/content/10.1101/2020.02.06.20020974v...

https://www.medrxiv.org/content/10.1101/2020.02.06.20020974v...

I would say that it really dismisses smoking as a big factor then.

I wouldn't: https://news.ycombinator.com/item?id=22435408

The percentage of severe cases among smokers is definitely higher, although the sample size is small.

Looking at the numbers from Wei-jie Guan et al (https://www.medrxiv.org/content/10.1101/2020.02.06.20020974v...):

nonsmokers = 927 cases, 793 non-severe, 134 severe

exsmokers = 21 cases, 12 non-severe, 9 severe

smokers = 137 cases, 108 non-severe, 29 severe

That gives:

nonsmokers: 14% severe cases of presented

ex-smokers: 43% severe cases of presented

smokers: 21% severe cases of presented

The low number of ex-smokers as well as other factors (did they quit because of advanced smoking-related diseases, etc.?) makes that number hard to interpret.

But smoking carries a normalised average 40% increased risk of severe cases.

    100 * (21-14)/((21 + 14)/2) = 40

Isn't smoking much more common among the Chinese than this sample suggests? I would expect a random sample to include more smokers than not. It may imply that the act of smoking or the associated health states reduce the likelihood of infection, even if they increase the likelihood of a bad infection if it does land.

Or length of time exposed to air pollution, where smoking habit increases the likelihood of mortality?