I wrote a long response but sense that we aren't getting anywhere, so I'll just share a video from a Leftist perspective---again, I AM a Leftist and always have been---that is about precisely how global bodies can ignore sovereign governments, especially when those global bodies are backed by powerful interests, be they countries, corporations or billionaires.
In short, dismissing the growing power of the WHO ignores the last 50 years of "post-colonialism" where the global north put lipstick on the pig of colonialism and continues to extract wealth from the global south, all in the name of "helping them."
I just wish people like yourself, who I can tell are very intelligent, could listen to the Leftist critique of the things you believe, rather than how so many assume any critique comes from the Right. Perhaps sharing this video, rather than me wasting words, will be an opening.
Anyway, I wish you well and I have appreciated our exchange.