it happening in China does matter. China isn't mainland USA. Again, The Virus was first reported in China, December 31, 2019. First documented case in the US was 1/10/20. China is not Idaho. If theoretically if an epidemic situation happened in Idaho, precautionary isolation would have been perhaps quicker because of better communication but would not happen immediately unless scores of sick people (not just 1) started showing up at the hospital or clinics, such as if, say there were an outbreak of Hanta virus. And then it would be at least another 24 hours give or take for lab tests to be taken and the results analyzed. It might have been that the virus was brewing in Wuhan for awhile before China admitted what was going on but it is doubtful, since it was such a short time between when they announced it and when the first American tested positive for the disease after traveling there.