[chucker]

Well, we don't know anything. We can make models, and then predictions based on those, and the more data we gather, the more certain we can be about certain things, but never quite 100%.

Do we know for a fact that the vaccine is 100% safe? No. We also don't know for a fact that there's a 0% chance there'll be a meteor crater tomorrow. We can be relatively sure based on constant surveillance, but what if we're overlooking an edge case?

What we do know is that tens of millions of people have been vaccinated, and very, very few had significant complications.

(This post kind of sounds douchy-er than I had intended. I guess what I'm saying is — yeah, it'd be nice if we had years worth of data, but that's kind of impractical, and the best scientists of the world are on the case. If there's a problem, you'll probably know rather quickly.)