There are many factors, but I will throw a guess.
We know the Wuhan flu severely compromises your immune system. Therefore, in addition to morbidity factors such as obesity, diabetes, or other preexisting conditions, if you are carrying the common cold virus, pneumonia, or influenza those boogers have a chance to flourish with a compromised immune system.
I have not seen much written about this, but people in NYC are in close contact with one another via public transit and just the usual crush of humanity. I suspect the average New Yorker carries more of these boogers than the rest of us because of this increased exposure/contact.
The Wuhan flu is grabbing the doctors attention and the headlines, but the other illnesses don’t go on vacation or step aside for it. If you carry pneumonia you will be in bad shape with Wuhan flu. Same for influenza A or influenza B. Even the common cold would be uncommon if you exhibit Wuhan flu symptoms! Same for gut bacterial infections.... we have heard anecdotal stories about patients having GI issues with this illness.
That does not mean it is a direct result of this new virus - it may just present because the immune system is overwhelmed and it can no longer fight off much of anything.
Other theory that I have read, and make some sense, is that it’s not just *an* exposure that can get you sick, but the number and length of the exposures - i.e. once you are swimming in a petri dish of the virus, crammed in with other people who are also sick (whether or not they have symptoms), the more frequent exposures makes you more likely to get sick, and the more exposure you get, the more likely that you will become even sicker - don’t know if that holds up to scientific scrutiny, but makes some sense to me.