I doubt there's anybody on GBO with the credentials to make a credible assessment of covid, or any of the vaccines, or combinations of vaccines, or the mixing with other vaccines.
Anybody, can find "absolute proof" of their stance on this issue, or any other issue on the internet.
My stance is: Hell, I don't know. I'm like a lotta other folks that are skeptical of a new untested vaccine that kills some folks, and doesn't really affect others.
I'm skeptical of a flu virus called covid-19, that kills some folks, makes some sick, but they recover, and doesn't make others sick at all.