Great news !
It’s good to know that flu vaccination has two benefits
replies(1):
No, but correlation isn't meaningless either. This study [1] appears to be as robust as one can get without doing a double-blind trial. Given the effect size, I suspect that is in the works.
[1] https://content.iospress.com/articles/journal-of-alzheimers-...
And with a proper survey, you can actually account for a lot of these effects. (Ex: after accounting for outdoor temperatures, the Ice Cream Sales / Drowning correlation can be largely factored out).
Imagine thinking this study and those datasets are remotely the same.