This is why I think a huge number of Chinese students who returned to the US in january are going to be vectors. They rode on buses, trains and planes that probably ventured to Wuhan at least once.
And why I think this may have started elsewhere and just got amplified in Wuhan.
That is why there should have been a embargo when Ten i (Xi) announced a quarantine of a Chinese city.
There is US precident of embargo of travel from a foreign country...that from Portugal to the state of Massachusetts from the 70's to the 1980's. That embargo was for air flights and shipping to that state.