The following statement is about as close as this site gets to a PSA (public service announcement): If you’re eligible, get the Shingrix vaccine against shingles.
Vaccines in General
This statement is about as close as this site gets to being political: Vaccines work. Anyone who denies this should quit reading now. I still can’t believe that what should be a question of science, medicine, research, and statistics has become so divisive. But that is the world we live in.
I’m not saying vaccines work for everybody, that they are 100% effective, or that some people haven’t had bad reactions to them. Nor am I saying that we don’t need more studies on the safety and efficacy of the vaccines we have now. I’m saying that, on balance, we already know enough to confidently say that, for most people, the benefits of getting vaccinated far outweigh the risks and costs.
The Shingles Vaccine
If you’ve had chickenpox as a child (as most people old enough to read this site have), you are at risk of developing shingles later in life. Older adults are most at risk, and the CDC recommends that people over 50 get the shingles vaccine. Since 2020, the only vaccine against the shingles virus available in the US has been Shingrix.
The varicella-zoster virus that causes chickenpox stays latent in your body long after the chickenpox has cleared. The virus can hide in your nerves and skin. For reasons that are not well understood, something can trigger the latent virus to become active and cause shingles. The Shingrix vaccine is very effective at preventing reactivation of the virus.
Getting shingles is nasty by all accounts and certainly something to be avoided. But honestly, getting the Shingrix vaccine is a fairly serious undertaking. It requires two shots, spaced 2 to 6 months apart. The first dose can cause side effects severe enough to lead some people to skip the second dose. Some health insurance plans also do not cover the cost of the vaccine.
For me personally, if the Shingrix vaccine only helped prevent a future bout of shingles, I probably would not have bothered with it. It did not seem worthwhile to get two shots merely to avoid a painful rash that lasts a few weeks and rarely causes serious complications afterwards. But then I read that the Shingrix vaccine might reduce the risk of developing dementia. From personal family experience, dementia is something I will endure many more inconveniences to avoid. I scheduled my first Shingrix dose the same week I learned of this possible link.
Shingles and Dementia
The emerging finding is this: shingles vaccination appears to be associated with a meaningful reduction in dementia risk over the following years.
One notable study of this possible link is a 2025 paper, A natural experiment on the effect of herpes zoster vaccination on dementia, which reported a roughly 20% reduction in dementia diagnosis risk among people who received a shingles vaccination compared with otherwise similar people who did not.
The study was interesting because it took advantage of a health-policy detail in Wales. Beginning in 2013, people born before a specific cutoff date were ineligible for the shingles vaccine, while those born after the cutoff were eligible. This allowed the researchers to compare two demographically similar groups whose members differed in age by only a few weeks: one group was eligible for and was likely to receive the vaccine, while the other group was not eligible and remained unvaccinated. Thus, this study avoided some problems that confound studies that just compare vaccinated and unvaccinated groups – if the only criterion for being in the vaccinated group is having received the vaccination, it is not possible to fully control for other differences between the groups. For example, vaccinated people may be more health-conscious and take better care of themselves, or they may be more likely to receive other vaccinations that could possibly affect dementia risk. By exploiting this policy situation in Wales, the study was able to create groups in which membership was decided only by an age difference of a few weeks, which should have a negligible effect on dementia risk. It seems very unlikely that this slight age difference correlated with any other systematic difference between the groups. Thus, the study provided evidence that the reduction in dementia risk was specifically associated with the shingles vaccine, which strongly suggests a causal link.
That study examined a live-attenuated varicella-zoster vaccine called Zostavax, which is no longer available in the US. This article describes a more recent study of the Shingrix vaccine and reports a 33% reduction in dementia risk. Another paper, Recombinant zoster vaccine is associated with a reduced risk of dementia, studied Shingrix (which is a recombinant vaccine rather than a live-attenuated vaccine) and reported an impressive 51% lower risk of dementia after participants received both doses. But it is important to note that this study could not establish a strong causal link between vaccination and dementia reduction, for the reasons outlined above.
Interestingly, some studies reported a stronger risk reduction in women than in men.
Why This Link Is Plausible
There are several biologically plausible mechanisms by which preventing reactivation of the varicella-zoster virus might reduce the risk of dementia, although none has been fully proven. The dormant virus has been found in the brain, where it can take up residence in nerve cells. Preventing its reactivation may therefore reduce inflammation that could damage the brain. Somewhat surprisingly, reactivation in the brain and the resulting inflammation may cause only subclinical symptoms or no symptoms at all. Keeping the virus quiet may prevent not only a painful inflammatory shingles outbreak in the skin but also inflammatory damage in the brain. And the brain does not heal itself as readily as skin.
Conclusion
The finding does not mean that getting the Shingrix vaccine is guaranteed to prevent dementia. It is simply a promising possibility, and for me it was convincing enough to get vaccinated. The experience was straightforward: my insurance covered it, I was able to get the shot at my local pharmacy, and I had no reaction beyond slight soreness at the injection site. I have my second dose scheduled in about two months.
There are, of course, many other things you can do to help reduce your risk of dementia. This Alzheimer’s Association article is a good summary. Note that the “intellectual activity” promoted by Retired Thinker gets a shout-out there as a preventive measure.
And please note: this post is for general information and discussion; it is not offering personal medical advice. I am not a medical doctor, nor do I play one on TV.
