Then a few people died nearby, and astrazeneca was temporarily removed from the list of options and wasn't recommended anymore. But the other three vaccines were safe and effective.
Then a young girl died here from from a J&J vaccine (the popular choice, due to it being a single-shot one), and we stopped using that. Suddenly the "classic" vaccines were not ok anymore, and the "all four are safe and effective" became "you should get a mRNA vaccine".
Then a bunch of young men ended up with heart issues after the moderna vaccine, and suddenly only pfizer is "safe and effective".
Also the "95% chance you won't get symptomatic covid" became a slightly "lower chance of hospitalizaton or death".
All of this of course came after the "masks are ineffective and you don't need them" that almost literally overnight (it was over a weekend) changed to "masks are mandatory in xyz places".
I mean sure.... science, conspiracies... but if you want to fuel a conspiracy theory, the best way to do it is to say something, then change what you said, and ban people who continue saying what you said a few days earlier.