[spupe]

> They can't claim causation if they don't understand the underlying reason for the change. That's not how science works.

Sorry but I had to nitpick here. This is exactly how science works. We first observe things that we cannot explain, and we can definitely infer causation without a complete mechanism or even a proper theory for it.

[sweetdreamerit]

It's a little more nuanced. Causation can be inferred in an experimental design. If the researchers can manipulate the independent variable (the vaccine) using an experimental and a placebo group, and then they can measure a statistically (and clinically) significant difference, then we can assume that this is not just correlation.