I think the biggest concern is it seems quite capable of killing people that tend to be in the generally healthy age range.

Diseases that do that often do so by causing (even if indirectly) the person's own immune system to overreact or otherwise go haywire.

I belive SARS had a similar impact.

My son had a situation where his immune system overreacted. We had folks from the local university on call for updates every few hours and etc. Doctors have very few things at their disposal that they can do when that happens and they get really nervous.

My son pulled through but it was an enlightening / scary moment to see doctors that concerned / with few options.