Unfortunately evidence seems to indicate that everyone getting once is also not very effective, the reinfection protection of past infection seems to be sub-20% from Omicron. You can find lots of studies with different numbers but none of them are good.
China's behaviour with respect to vaccines is very strange, they could mandate vaccination very easily, they could also relent and import mRNA vaccines but they don't. It seems like even mandating their very poor vaccines would be helping their situation a lot if it had been done months ago - availability has not been enough.