How the Virus Got Out
nytimes.com
nytimes.com
If we had known the virus was this contagious at that time, more countries could have prepared and put a stop to travel from some of these areas.
It happened way too late with Italy, which is why the cases skyrocketed.
I've seen reports that patient zero in Wuhan was back on November 16th. I know many people that had symptoms (including myself) at the end of November/early December.