Why is the epidemic in Wuhan so serious?

Wuhan City, Hubei Province is the first city in China where avian influenza broke out. At the beginning of the epidemic, people really didn't know COVID-19, so they didn't control it in time, which led to a large-scale outbreak.

It may be that the epidemic did not attract too many people's attention at first, or it may be that the control was not enough, so that more and more people were infected later, and the whole city of Wuhan was closed on New Year's Eve. Only then did people realize the seriousness of the problem, but with the joint efforts of the people of the whole country, they finally got through the crisis.