Shingles vaccination may reduce dementia risk

The study isn't _just_ that week, it's over every person that received the shingles vaccine since 2013 in a program that said "if you are born after 9/2/33 you can get the shingles vaccine, and if before then you cannot". This study is over all people in that program (~300k people), regardless of exactly when they were born. The study found an 8% reduction in dementia diagnoses that correlates entirely to whether the person's DoB was before or after that date. Presumably the only reason they don't say "to the day" is because the number of people involved makes statistical variance too high (and lets be honest there's probably some fudging of people's DoB if you're one day off no matter the rules).

it's huge for something that should be close to zero if the vaccine had no effect.

Depends on what the actual risk is:

> Using our regression discontinuity approach, we find that being eligible for the zoster vaccine caused a 1.3 (95% CI: 0.2 – 2.7; p=0.022) percentage point absolute, and 8.5% relative, reduction in the probability of a new dementia diagnosis over our seven-year follow-up period[0]

1.3% absolutely reduction seems like a big deal.

[0] https://www.medrxiv.org/content/10.1101/2023.05.23.23290253v...

Although the magnitude is small, the interesting thing here isn't that you could get a shingles vaccine to marginally reduce your dementia risk, but that if one virus can cause dementia, it's probably not the only one.