Do we know positively the Communist Chinese do not have a vaccine? I personally believe very little of anything coming out of Communist China.
China, like all countries, has its share of traitors, that would leak that information to us.(And we should also have our own spies over there.)
If China does have a vaccine for covid19, and our intelligence agencies found out, it would not be leaked to us citizens.
I am sure our country , Russia, Iran, Israel, India , North Korea, etc. are also working on biological warfare, along with nuclear warfare weaponry. -Tom