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.
There are still ongoing outbreaks in China, and there was a fairly well publicized one in Hong Kong. The reason you’re not hearing about them elsewhere in the mainland is because of Chinese control of the press, plus the Chinese definition of “lockdown” is a lot different than ours. They simply shot anyone out violating curfews or lockdowns and disappeared the body.