#21

I’m not following. How does this r/o healthy user?

#22

Let’s say the vaccine is introduced for people born after March 3rd 1950 and you show that people born in the weeks after that date have 20% less dementia than people born before. There’s the same % of healthy people born in March 2nd and March 3rd. The difference is not different healthy behaviors between these cohorts due to an arbitrary date picked in the calendar. It’s the vaccine. That’s what they did (if I reckon correctly).

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#23

But that’s true only if everyone receives that vaccine. If vaccine is Optional then maybe healthy people are choosing the vaccine?

#24

The effect is irrespective of being vaccinated or not: Causal evidence that herpes zoster vaccination prevents a proportion of dementia cases 2023 (:warning: Preprint but Stanford + CZI)

image

Before the cutoff date: no one is vaccinated (0.01%). After the cutoff date: half the population is (47.2%). And overall, no matter their vaccination status, people born after the cutoff date had a lower rate of dementia.

Other researchers (Oxford & UCL) looked at the cutoff date for the new shingles vaccine and also found that people who got the new one in the 6 months following the change had lower rates of dementia compared to people who got the “old”/less effective one 6 months before the change: The recombinant shingles vaccine is associated with lower risk of dementia 2024. Here again, these people are as healthy. It’s just that some got the new vax, some got the old one, because the version was changed at the national level.

I think there were one or two other papers replicating these findings in Australia. Should these preprints be peer-reviewed and confirmed, then the evidence will seem compelling to me.

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#25

Here’s the “Australian” one: Herpes zoster vaccination and new diagnoses of dementia: A quasi-randomized study in Australia 2024 :warning: Also a preprint, by the same Stanford/CZI research team as the 2023 one above.

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#26

If it happened instantly, and it didn’t matter whether you were vaccinated, then the results are not attributable directly to the vaccine. At least I don’t see a mechanism for that.

#27

Because 50% of the population born after the cutoff date is vaccinated. So of course the results are attributable directly to the vaccine. But because we look at the whole cohort, and not only vaccinated people, we exclude the “healthy user” effect.

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#28

From this study it appears that the type of shingles makes a difference in cause. HZV vs HZO - I did not know there were 2 types of shingles…

The overall adjusted effectiveness of Shingrix for prevention of HZO was 89.1%.

In the outcome of incidences of Herpes Zoster ophthalmicus (HZO), the generic inverse variance showed a statistically significant association between patients who have HZO and increased incidence of dementia

Conclusion:

Our study showed no significant association between HZV and the incidence of dementia or Alzheimer’s disease, but it shows a significant association between HZO and the incidence of dementia. More multicenter studies are needed to establish the actual association between the HZV and dementia.

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