Could a simple calculation be then that a vaccination is preferred if the vaccine that is taken will prevent at least (1) infection within the immune period? If the efficacy is 50% for example, then it would be (2) infections. Since the pathogen is worse than the vaccine, maybe 40% for a young person it could be 0.6 and 1.2 infections instead, maybe. It depends how solid the Alzheimer’s data is for example as well. What would your numbers be?
How do you stand with regards to Valaciclovir, an antiviral, taken as a prophylactic to prevent infection from the herpesvirus family (Shingles - Alzheimers, EBV - Multiple sclerosis, etc)?
Toll-like receptor 4 and CD11b expressed on microglia coordinate eradication of Candida albicans cerebral mycosis
Microbes, including fungi, routinely infect the brain, but specific immune pathways are undefined. Wu et al. show that Candida albicans activates microglia through two mechanisms involving the production of amyloid b-like peptides that signal through TLR4 and candidalysin that activates CD11b, together promoting clearance of albicans from the brain
Michael Lustgarten has a video on Rapamycin and Candida that shows huge effect on Rapamycin and Candida infections in the brain, basically if you use Rapamycin you will have very little Candida growth and almost none in the blood stream witch equals much lower incidences of Alzheimers. Coincidence, I don’t think so.
I don’t have it, I cam across it on youtube a couple of months ago. But it is not like his typical videos, it’s a stand out. I will try to find it later today.
Won’t an aspect like the reduced risk of Alzheimer from some vaccines, if this is causal, be likely to more then offset the effect of reduced immunological space?
“We then show that receiving the herpes zoster vaccine reduced the probability of a new dementia diagnosis over a follow-up period of seven years by 3.5 percentage points (95% CI: 0.6 – 7.1, p=0.019), corresponding to a 19.9% relative reduction in the occurrence of dementia.”
Besides probably causing a reduction in Alzheimer, the vaccinations guard against the diseases they are meant for. Can’t the combined effect be likely to yield a net benefit to most people?
Any opinion on taking an antiviral as well?
Because I have an APOE4 allele, about 3 x causal increase in risk for Alzheimer’s - it is very worth it to me with vaccines.
Antivirals could be of benefit and they would not cause a reduction in immunological space. They might have some other side effects though. I can’t say I have looked into them much at all so I can’t give a good opinion on them.
The BCG (Bacillus Calmette-Guérin) vaccine was developed against Tuberculosis over 100 years ago, but it is known to protect against other infectious diseases as well. A Phase III randomized clinical trial from Harvard shows that multiple doses of theBCG vaccine protected adults with Type I diabetes from COVID infections better than the initial mRNA COVID vaccines. It also protected this group against other infectious diseases. The BCG vaccine worked against COVID variants Delta and Omicron in this study.
Some professions like nursery workers and healthcare care workers are exposed to far more infectious pathogens in the course of their careers than the average person let alone more solitary professions like crop farming. I would have thought this would place a far greater burden on finite immunological memory than a few optional vaccines.
Is there any evidence that these people have weaker immune systems as a result?
It’s not necessarily going to put a far greater burden on immunological space than vaccines. Vaccines are designed to create a response resulting in a strong immunity, which will take up a decent amount of immunological space. But it’s hard to compare these things. I can’t say whether getting lots of vaccines matters more or less than getting lots of infections over a lifetime. I haven’t looked into that, and the studies I read on immunological space did not talk about that.
I’m not aware of direct evidence that people exposed to more pathogens have weaker immune systems or less immunological space at older ages, but I can’t say I have looked at the literature on this in any detail. It would be interesting to see studies on immunological space in people with very different life histories when it comes to infection exposure.
In contrast to the beneficial off-target effects reported following neonatal BCG in infants, a small increased risk of symptomatic febrile or respiratory illness was observed in the 12 months following BCG vaccination in adults.
It seems like adults could also get vaccinated just for the sake of anti-aging. Even though RCTs show no real benefits, there aren’t many risks either—it feels like a ‘better than nothing’ situation. I wouldn’t make it a priority, though. @KarlT@DrFraser@RapAdmin
I’m fascinated by vaccines and association data in regard to Dementia. So I had Vera-Health.ai do it’s best with the common vaccines. I guess my conclusion is, there are much better options to use than BCG vaccine. Additionally, I doubt that risk reduction is additive; and once there has been some risk reduction, adding another vaccine will almost certainly have diminishing returns.
Looks like Shingles Vaccine is a good one to start with; and furthermore, if one has HSV-1 IgG Ab, strongly consider 500 mg of Valacyclovir daily … which also will suppress VZV in addition to HSV-1. Interestingly, no increased risk of dementia if one has HSV-2.
Percent dementia reduction (vaccine-specific; “regular schedule” where data fit that use)
Vaccine
Best available % dementia reduction (from provided sources)
Systematic review/meta-analysis (21 observational studies; n=104,031,186), Age and Ageing 2025; vaccine-type pooled association across heterogeneous cohorts 4
16% lower risk with 2–3 doses (HR 0.84) and 57% lower risk with ≥4 doses (HR 0.43)
Incident dementia; high-risk populations only
Systematic review/meta-analysis (8 cohort studies; n=9,938,696), Age and Ageing 2025—most relevant numeric estimates for “regular schedule” over multiple years; not significant in overall population (HR 0.93) 5
Pneumovax (PPSV23) / pneumococcal vaccination
No single pooled “any dementia” % in provided sources; 33% lower AD risk (RR 0.67) and 36% lower AD risk (RR 0.64) reported in 2 meta-analyses (AD ≠ all-cause dementia)
Alzheimer’s disease risk (not all-cause dementia)
Two observational meta-analyses: Frontiers in Immunology 2022 (pneumococcal OR 0.71 → 29% lower AD risk) 6 and Age and Ageing 2025 (pneumococcal RR 0.64 → 36% lower AD risk) 4
Tetanus + Diphtheria (Td/Tdap)
33% lower risk (RR 0.67) (any dementia)
Incident all-cause dementia
Observational meta-analysis (21 studies; n=104,031,186), Age and Ageing 2025 4
BCG (routine vaccination)
Not available in provided sources
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Available estimates are primarily from intravesical BCG in bladder cancer (not routine vaccination), and a bladder-cancer meta-analysis reports HR ~0.63–0.65 but with high heterogeneity and “minimal if any” effect—this is not generalizable to routine BCG schedules 7
RSV (routine older-adult vaccination)
Not available as a schedule-based % in provided sources
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One NPJ Vaccines propensity-matched cohort reports reduced 18-month dementia risk after AS01-adjuvanted shingles/RSV vaccines, but the abstract provided does not include a percent/HR and follow-up is short 8
COVID-19
Not available in provided sources
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No human observational/clinical estimates of dementia reduction after COVID vaccination are provided here (only animal/other outcomes) 9
Bottom line (using the provided sources): the strongest and most directly schedule-concordant dementia-risk reduction signal is for recombinant zoster vaccine (2-dose series) (about 51% lower dementia risk vs unvaccinated in a large matched cohort) 1, while influenza and Td/Tdap show modest-to-moderate associations (with a notable dose-response for repeated annual influenza vaccination in high-risk groups) 5 4.
