Pat, as far as I know there is no final (scientific) answer to that question (yet). Most experts seem to agree though that "mix n match" is a workable strategy with covid vaccines. Personally I don't think a different vaccine will be available in Dumaguete before it's time for my second shot of Sinovac, but even so, if at some later stage I can get a booster shot from a different one, I'll be in line for that.
Hopefully the different LGU's will manage to better organize the vaccination effort, which, if I go by the Dumaguete example, is in need of streamlining and decentralisation if the pace of vaccinations is to speed up. 5,000 to 8,000 doses per day in Negros (about 5 mln people) would still mean 2.5 to 4 years of non stop vaccinations, 7 days a week, to reach everyone. A more speedy effort (assuming enough vaccine will be available) would mean at least 10 times that many vaccinations per day are necessary, something the current setup can't possibly handle.
And it is possible that before 2.5 years have passed, a new variant will emerge to make the current vaccines useless (or near to). The whole world needs a very fast vaccination program but with 8 billion souls around, it is not likely.
Again, I said "if". I know it is not a current requirement. If the US (or airlines that fly there) decide you must have one and they don't accept the the Chinese vaccine then it is worthless to me. The WHO has absolutely zero authority over any government or corporate policy. They can only make recommendations, nobody is obligated to follow them. I will avoid that risk and go with one of the other vaccines that is more widely sought after and accepted worldwide.
"And many countries don't accept the Chinese or Russian vaccine. The US being one." The plain meaning of the above is that the US is one of the countries that doesn't accept the Chinese or Russian vaccine, Rye. Did you forget what you wrote? Write what you didn't mean? Or just backpedaling?
