Last updated on February 1st, 2026 at 11:44 am

I have written several articles about the shingles vaccine reducing the risk of dementia. Recently, a study from Canada seems to provide even more evidence of reduced dementia risk from the vaccine.

The most important benefit of the shingles vaccine is preventing shingles, which is caused by the Varicella zoster virus, the same virus that causes chickenpox. Shingles is a painful and disfiguring disease.

This article will review this new research and what it may mean for reducing the risk of dementia.

Shingles and the vaccine

Shingles is a complication of chickenpox, caused by the Varicella zoster virus (VZV). The body’s immune system does not eliminate VZV after chickenpox. Once the symptoms of chickenpox disappear, the virus stays in the dorsal root ganglion, a bundle of nerve fibers at the bottom of the spinal column. The virus stays there, hidden from the body’s immune system.

Even though the body developed an immune response to the original zoster virus infection, several years or decades after the initial infection, the adaptive immune response against the virus wanes or disappears. Due to other unknown factors, possibly stress or other infections like COVID-19 or VZV, the virus “moves” along nerve bundles and initiates a secondary infection with much more serious consequences for the individual.

This second VZV infection, called herpes zoster, is more commonly known as shingles. Shingles usually occurs in adults older than 50, although it can occur at any age, even in young adults. 

Even though the same virus causes chickenpox and shingles, shingles was given a different name, herpes zoster, probably because it was originally thought to be caused by a similar, but unrelated virus.

Shingles is an entirely unpredictable disease. It reactivates due to unknown causes. Once shingles appear, they can be painful, depending on the location of the outbreak. It can cause blindness (from herpes zoster ophthalmicus), disfigurement of the infected area, permanent pain (postherpetic neuralgia), and other conditions.

Shingles can be treated with antiviral drugs, but only if the infection is recognized and treated within 24-72 hours, which means the stricken individual must seek treatment quickly.

Post-herpetic neuralgia pain may last for weeks, months, or even years after the blisters have healed – this is not a trivial disease.

Shingles is not a one-time event. After you develop shingles, it may return in months or years, so it is important to be vaccinated even if you have had shingles.

Almost all individuals in the US aged 50 years and older have been infected with VZV (from chickenpox) and are therefore at risk for shingles. There’s a growing body of evidence that herpes viruses, including VZV, may be linked to cognitive decline.

The only way to prevent a shingles infection is to boost the immune system with a vaccine against the zoster virus. The CDC recommends Shingrix (also known as the zoster vaccine, available in the USA), a relatively new, safe, and effective vaccine that prevents shingles. Shingrix has replaced the older shingles vaccine, Zostavax, because Shingrix is much more effective.

There is another way to prevent shingles — never get chickenpox in the first place. Of course, we have a vaccine for that, the chickenpox (or varicella) vaccine.

The CDC recommends the shingles vaccine for individuals 50 years or older. Additionally, the vaccine should also be given to individuals who are 19 years or older and have a compromised immune system. Other countries have different recommendations, so check your country’s public health authorities for recommendations.

So let’s be clear about a couple of things. First, you are only at risk for shingles if you have had chickenpox. Second, children who have received the chickenpox vaccine probably will not develop shingles as they age.

Shingles vaccine and dementia study

In a study to be published in February 2026 in The Lancet Neurology, Pascal Geldsetzer, MD, PhD, Stanford University, California, and co-authors examined a quasi-randomized rollout of the shingles vaccine in Canada that occurred in 2016. Ontario residents who turned 71 on or after Jan. 1, 2017, were eligible for free shingles shots, while those who turned 71 before that date were not.

Geldsetzer and colleagues studied patients born from 1930 through 1960 who were registered with a primary care provider in the Canadian Primary Care Sentinel Surveillance Network.

Ontario’s date-of-birth eligibility split patients into three groups: those ineligible (born before Jan. 1, 1945), those eligible for 3.5 months (born in 1945), and those eligible for at least 1 year and 3.5 months (born Jan. 1, 1946, through Sept. 15, 1951). The health characteristics of patients at baseline were similar for those born immediately before or after the two eligibility cutoffs.

Here is the key result:

• Being eligible for a free live-attenuated zoster vaccine (Zostavax, which is no longer available) was associated with a reduced probability of a new dementia diagnosis by an absolute difference of 2.0 percentage points over 5.5 years.

The researchers concluded:

This analysis of natural experiments provides evidence, which is more likely to reflect a causal relationship than previous evidence from more standard observational data analyses, that herpes zoster vaccination prevents or delays incident dementia. Mechanistic research into this effect could provide insights into the pathophysiology of dementia and maintenance of neuroimmune health in older age.

Summary

This study was not powerful since the difference in risk was small, and since they couldn’t identify vaccination status, just whether the individuals were eligible for the vaccine.

However, it was large enough in size that it showed a reduced risk of dementia.

Nevertheless, this study does add to the growing body of evidence that the shingles vaccine appears to reduce the risk.

The reader might wonder why. Researchers are unsure. For example, there might be a non-specific immunomodulatory neuroprotective effect of shingles vaccination. On the other hand, shingles itself might increase the risk of dementia, suggesting pathogen-specific mechanisms.

Whatever the reason, get the shingles vaccine if you’re in the appropriate age group. It prevents a nasty disease with the added benefit that it may reduce your risk of dementia.

Citations

• Pomirchy M, Chung S, Bommer C, Strobel S, Geldsetzer P. Herpes zoster vaccination and incident dementia in Canada: an analysis of natural experiments. Lancet Neurol. 2026 Feb;25(2):170-180. doi: 10.1016/S1474-4422(25)00455-7. PMID: 41579903.

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