Earlier quoted context omitted.
Indeed there is a link but we don't even know the direction of causation. I find it quite plausible that people with as-yet undiagnosed early-onset Alzheimer's forget to get flu shots.
Yet, you also find it plausible that people who spent years on this project would never have thought of that. Your misplaced trust in your own plausibility filter causes you to make foolish posts on HN.
I find it plausible that the few people who spent hours reviewing this paper didn't think of that, and that the people publishing the paper ignored it since ignoring it could help them gain more funding.
> Your misplaced trust in your own plausibility filter causes you to make foolish posts on HN.
It is foolish to believe that scientists does things properly. As an outsider you only see the outlier results, meaning that most of what reaches HN could be faked or statistical trickery or have simple explanations due to poor science since poor science is more likely to produce headlines, while most scientists could still do the right thing.