Something very unusual from an infectious disease viewpoint. There is little doubt that the pandemic began in Wusan and severely affected the local population. It spead like wildfire to Iran, Europe and the United States. Yet somehow, someway other Chinese urban centers and regions seem to have been spared. Even though Chinese reporting numbers is sketchy at best, it would be hard to hide the big outbreaks that are now occurring in Europe and the US. It appears the Chinese have “herd immunity”. That is to say the majority of the population has been made immune. Just how that was accomplished has some natural and some scary scenarios. If the majority of your population were over the years exposed to many bouts of different subtypes of corona virus, it is possible that the exposures resulted antibodies or delayed T cell immunity that had a protective effect against COVID-19.No doubt the Chinese will offer this or a similar explanation. Yet, and if you were designing a biological agent as a weapon, it would be incumbent first to render most of your own population to be immune to the virus.
It is a very good question as to why there were apparently no major outbreaks in China other than in Wuhan.
The lockdown in Wuhan is not a sufficient explanation, because millions of Chinese left the area before the lockdown.
Most curious.