They completed all of the normal testing. The mRNA vaccines technology is decades old. They did all of the normal testing but the stages were done in parallel and pushed ahead of everything else in the pipe. Had any stage failed the approvals would not have been given. This is an anti-vax meme but it is completely false.

But I am profoundly against the heavy handed tactics used in deploying them.

Ah yes, the heavy handed tactics of checks notes zero consequences to the people who didn’t take it.