Go travel the world.
Go there and see!
Was it 1991, when common sense was redefined as "whatever the global hegemon is doing"?
Was it 2017, when Washington decided China was their ultimate adversary and can do nothing right?
If I wasn't being clear, there are 2 major reasons why China refuses to open up: ineffective domestic vaccines and few hospital beds per capita. The CCP fears a total healthcare system collapse and subsequent discontent from its citizens.
You should know these basic facts.