As @clacke@libranet.de pointed out, the Wuhan outbreak currently has an estimated fatality rate of 2%, which is extremely high. Fortunately, it has only infected a very small number of people.
Compare to its relative #SARS which struck around 8,000 people over a period of a year or two, killing nearly 10%.
In either case, due to the high death rate, the key thing is to contain its spread, so it doesn’t become widespread like influenza.
Also there, a 2nd US case confirmed on 2020-01-24, this time in #IL. Like the first, the traveler had recently been to Wuhan, China.
Also, there's no way to know yet whether further analysis will show a much lower death rate (e.g., many more infections where the person never felt sick enough to bother going to the doctor).
(Shared because I have seen some people who already seem spooked over this.)
I personally think this level of infection would be difficult to hide for more than a few days. Despite quarantine rules, people in the hardest hit areas would probably start fleeing by foot looking for ways to save themselves.
Based on the Taiwanese newspaper capturing the temporary leak of "real" numbers, (154,000 infected and 24,500 killed ... see https://www.taiwannews.com.tw/en/news/3871594 ) this was probably an overestimate, but probably not over 2-3X the actual numbers at the time.