Considering the air and water quality in China which has for years already affected most of China’s city peoples it’s not surprising they would be acceptable to any resperatory virus or illness.
I was thinking about that too. Not sure how bad the air quality is in Wuhan, but there are studies that show chronic smoking and vaping make you much more susceptible to the flu.
Living in a polluted city has got to have the same effect.
Living in an extremely densely populated city is going to dramatically increase the R factor.