> I'm arguing that we don't know what could go wrong or what the probability something can go wrong is in the long term because the data literally just doesn't exist

Yeah, but we also don’t know the long-term risks of HDTVs, VR headsets, CBD oil or Impossible burgers. Not knowing the long-term risks of a product is exceedingly common.

> you're trying to argue that we should just assume that the probability of something going wrong is already established as infinitesimally small.

Not at all. I’m saying that you have to encounter this problem nearly every day. And that if you were consistently concerned about abstract, undefined, unknown potential risks that you had no knowledge or understanding of then you would not participate in any new medicine, technology or activities and I just don’t know of anyone that follows that philosophy consistently. So that’s why I’m not buying that 0 long-term data is the only reason or even the main reason someone wouldn’t take the vaccine.

A chocolate bar from a brand new chocolate company at the grocery store is familiar and easy to understand. No one studied the long-term effects of this substance you’re about to put into your body (because it was just released this month), but we assume that the ingredients are correct, we assume that we understand the effects the ingredients will have on us, we assume that someone inspected the facility for cleanliness and we assume that it was delivered to the store and stocked without being tampered with. The long-term data for this particular bar of chocolate for this new brand doesn’t exist, but you don’t care and don’t think twice about consuming it. So, that’s why I don’t think it’s about the data at all, I think it has more to do with our assumed individual knowledge of the product, the production process and the quality control (or when lacking that, our willingness to trust the relevant parties).

Even if you get long-term data, it’s a no-win scenario if you’re were never looking for anything specific in the first place. You had no hypothesis, no argument and designed no experiment.

Let’s say 2030 roles around and they announce: “No long-term negative effects!” Well, why would I believe that? My area of concern was infinitely broad. You can’t test to infinity, so you’ll never satisfy my doubts. There might still be negative effects coming in 10 years, or maybe you messed up in the data collection, or are just plain lying to me, how would I know? Why would I trust you? Only if I approach the problem with a specific, testable concern can I ever get reassurance that my concerns have been addressed.

It makes a lot more sense to me to say: I’m concerned about mRNA vaccines because Dr. X expressed concerns about Y. And then wait for that specific concern to be addressed.

> The data will exist eventually, we are not stuck in this permanent state of ignorance.

Only because people got the vaccine and didn’t wait for long-term data. That’s why this philosophy can never be adopted by a significant portion of the population, because it’s self-defeating. The moment you convince everyone that it’s smarter to wait for long-term data, you lose the ability to obtain that very data you want.