My point is that under normal circumstances we would test a vaccine out for 12 years. We would find out if there are long term health consequences like myocarditis or cancer. Obviously any long term health consequence would be "unintended" and therefore "unexpected" and "unanticipated". As a result we document everything and using statistical analysis determine if there were any significant signs of health risks. We don't "prove" them at this point in time, we merely document, analyze, and identify potential risks. It is possible that some completely unrelated factor affected our study, we will determine that at a later date and perhaps adjust our conclusions. But at this point, during clinical trials, we are looking for any warning signs, and the way we look for them is to document everything.