Key Takeaways
- Zostavax was linked to a 20% lower dementia risk in older adults over seven years.
- The effect was stronger in women, possibly due to immune differences.
- Findings apply only to Zostavax, not the newer Shingrix.
Getting vaccinated against shingles—a disease caused by the reactivation of the varicella-zoster virus—may be associated with a 20% lower risk of developing dementia, according to new research published in Nature.
Zostavax Shingles Vaccine. Credit: Whispyhistory
Researchers from Stanford University and collaborating institutions used a unique real-world setup in Wales to examine the potential protective effects of the shingles vaccine against dementia. Their findings suggest that this common vaccine, already recommended for adults over 50, may have off-target benefits for long-term brain health.
Why Investigate the Link Between Vaccines and Brain Health?
“Neurotropic herpes viruses may play a role in the development of dementia,” the study authors note. “Vaccines, especially live-attenuated ones, can trigger broad immune responses that may protect beyond their intended target.”
Shingles, also known as herpes zoster, is triggered by the reactivation of the varicella-zoster virus—the same virus that causes chickenpox. This reactivation becomes more likely with age and has been linked to chronic inflammation, which may contribute to neurodegenerative conditions.
A Natural Experiment: Eligibility Cutoff in Wales
To explore a possible causal link—not just correlation—researchers took advantage of a natural experiment in the UK: starting in 2013, eligibility for the live-attenuated shingles vaccine (Zostavax) in Wales was based solely on date of birth. Those born on or after September 2, 1933, were eligible to receive the vaccine for at least one year, while those born just one week earlier were never eligible.
By comparing individuals just above and below that birthdate cutoff—who are nearly identical in age and health status—the researchers were able to minimize confounding variables and simulate the conditions of a randomized controlled trial.
Key Findings from the Study
- Vaccination rates spiked from just 0.01% among ineligible individuals to 47.2% among eligible ones.
- Over a seven-year follow-up, receiving the shingles vaccine was associated with:
- A 37% reduction in shingles diagnoses (replicating known clinical trial data).
- A 3.5 percentage point absolute reduction in the risk of dementia diagnoses.
- A 20% relative risk reduction in dementia among those vaccinated.
These effects were stronger in women than men—a pattern consistent with other research on immune response and vaccine benefits.
“The dementia-protective effect was particularly pronounced in women,” the study notes. “This may be due to sex differences in immune response or dementia pathogenesis.”
How Might the Shingles Vaccine Protect the Brain?
The researchers propose two plausible mechanisms:
- Reduced viral reactivation: By preventing shingles (and potentially subclinical reactivations), the vaccine may limit chronic inflammation and viral damage to the brain.
- Immune modulation: The live-attenuated vaccine may enhance immune regulation through off-target effects, particularly in women and those without autoimmune conditions.
Importantly, the study ruled out other possible explanations like changes in healthcare use or unrelated birthdate-based policies.
Validation Beyond Wales
The findings were further confirmed using death certificate data from England, which followed a similar vaccine rollout. The replication in a larger population and with a different dataset (mortality records vs. health records) strengthens the case for a real, biological effect.
What This Means for You
While the shingles vaccine is not yet recommended specifically to prevent dementia, this study offers a compelling potential added benefit:
“If these findings hold true across other settings and with newer vaccines, shingles vaccination could emerge as a cost-effective strategy to help delay or reduce dementia risk,” the authors concluded.
Related Reading:
Flu Vaccination Linked to Lower Alzheimer’s Risk: What the Latest Research Reveals
Vaccines May Protect You Against Other Diseases Besides Those They Were Made for According To Study
The BCG a Tuberculosis Vaccine Boosts Immune Cells and Reduces Risk of Other Infections
FAQs
Can the shingles vaccine prevent Alzheimer’s disease?
Not specifically. The study measured all-cause dementia diagnoses, not Alzheimer’s alone, and did not differentiate by type.
Does this apply to the newer shingles vaccine (Shingrix)?
No. This study only looked at the older live-attenuated vaccine (Zostavax). Shingrix became available in the UK after the study’s follow-up period.
Should I get the shingles vaccine to reduce dementia risk?
The vaccine is already recommended for adults over 50 to prevent shingles and postherpetic neuralgia. While the dementia link is promising, it’s not yet an approved indication.
Bottom Line
This isn’t the first time a vaccine has been linked to benefits beyond its original purpose. The flu shot has been tied to lower risks of alzheimer’s. The BCG vaccine, once used for tuberculosis, has shown potential effects on autoimmune conditions like multiple sclerosis. Now, the shingles vaccine may have a role in protecting the brain.
But while the study design is clever, it’s not perfect. It looked only at older adults who received Zostavax, not the newer Shingrix, and relied on electronic health records, where dementia can be underdiagnosed or delayed. We also don’t know whether vaccinating earlier in life might offer greater benefit, or if the effect is limited to a narrow age range.
So, should we start viewing vaccines as a strategy for healthy aging? Possibly—but more research is needed to confirm whether the immune system’s response to these vaccines is what’s driving the protective effect.
The idea is compelling: a single shot that could help defend against both shingles and cognitive decline. For now, it’s a promising lead, not medical advice. But it does shift how we think about prevention—and what else common vaccines might be quietly protecting us from.
References
Eyting, M., Xie, M., Michalik, F. et al. A natural experiment on the effect of herpes zoster vaccination on dementia. Nature (2025). https://doi.org/10.1038/s41586-025-08800-x
Keefe, R.C., Takahashi, H., Tran, L. et al. BCG therapy is associated with long-term, durable induction of Treg signature genes by epigenetic modulation. Sci Rep 11, 14933 (2021). https://doi.org/10.1038/s41598-021-94529-2
Bukhbinder, A. S., Ling, Y., Hasan, O., Jiang, X., Kim, Y., Phelps, K. N., Schmandt, R. E., Amran, A., Coburn, R., Ramesh, S., Xiao, Q., & Schulz, P. E. (2022). Risk of Alzheimer’s disease following influenza vaccination: A claims-based cohort study using propensity score matching. Journal of Alzheimer’s Disease, 88(3), 1061-1074. https://doi.org/10.3233/JAD-220361
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