Regarding China shutting/not shutting its borders:
China shut down INTERNAL FLIGHTS pretty early (ie flights from Wuhan to other parts of China... while nagging its ASEAN partners and other countries to keep their own borders open to China (amid lots of sobbing and whinging from the Chinese Communist Party about how MEAN it would be for anyone to close their borders, and what a terrible effect this would have on the poor precious Chinese economy. I know, because I had to write up a report on some of the ASEAN meeting details).
They were happy to export the virus to other countries, while being careful not to spread it around other parts of China.
Once the virus was established in other countries, China immediately took steps to stop all flights from those countries into China.
Next time, the world needs to be prepared.
First whiff of the next dodgy new virus breaking out in China (or Chile, or Greece, or the US, or Ghana, or ANYWHERE), close the fucking borders and do it immediately, and anyone who is on a plane in the air at the time that the borders are closed will get quarantined for two weeks in a hotel airport when they arrive. Shut it down. Immediately. Close the borders.
No more listening to sob stories about "Why are you blaming us for this virus?" "You're racist!" "It will stigmatize us!" "It will damage our economy" etc. etc.