OK there are politics.
however your question was:
Why isn't the Chinese vaccine approved for use in the US or the EU when the WHO has approved it?
Tentative answer: because China owns the WHO?
Yes, politics. Politics everywhere.
It's worst than that... US, China, Russia...
"A mysterious marketing agency offered social media influencers payment to spread disinformation about Covid (Pfizer) vaccines.
Their plan backfired when some of the influencers exposed the requests to the world."
https://www.facebook.com/watch/?v=513641049920500And for a moment it makes you think what if it's other way around what if Pfizer pro-Pfizer's mad you say so.