Certainly travel from China, any citizen from China being barred from getting on an airplane heading to the US back in December would have helped. But remember the opthomologist in China who treated people and tried to get the word out about this new disease. He met extreme resistance from the Chinese govt and he eventually died from the illness.
This holding back of info is bad, dangerous.
The State of Ohio Public Health director stated yesterday that even though there are very few cases proven through testing they have tracked the flow to people with symptoms that lead them to calculate 10% of their population or 117,000 people will be in contact with the virus in just a week or two.
Airports like Seattle, Minneapolis, LA have tons of Chinese tourists and business people coming in all the time let alone others coming to the US from China.
Once the virus got into the US by mid to late January it was too late but maybe still better to limit travel from some locations.
It is stupid to bar travel from Europe but not bar Americans returning from Europe. But I am not sure what the legality is of barring US citizens from re-entering the country when an option is to quarantine them on their return.