Really tough to know any of this in any detail. Early on (December) doctors in Wuhan noted a significant amount of "atypical pneumonia" cases that resembled SARS. They started talking about it on Chinese social media and were quickly shut down by local officials and forced to apologize for spreading misinformation. So the outbreak was allowed to grow locally. Not clear at what point knowledge reached other parts of China but there were lots of reports on social media (twitter mainly) about the severity of the outbreak before China ever acknowledged it publicly.Was the sickness common knowledge in China BEFORE the rest of the world knew of it ? How many of the approx. 11,000,000 population of Wuhon escaped outside the first Wuhon quarantee zone ? I read an estimated 5,000,000 ? Who many of those escaped the second quarantee zone of approx., 56,000,000 ? (which is approx. Calif, Oregon, Wash combined.)
I'm not sure how much of it was people "escaping" from Wuhan because of the virus, versus the fact it was a time of year where many people in China travel. But a lot of people definitely left the Wuhan area before the quarantine was set in place. Interestingly, though, if you believe the numbers being reported, there has been relatively little disease outside of the Hubei area...so far at least.