A new cohort study showed that older adults at higher risk for dementia were less likely to have a dementia diagnosis after receiving the herpes zoster (shingles) vaccine.

These results are in line with other studies that have previously shown that the vaccine significantly reduces the risk of dementia or Alzheimer’s disease.

This post will review shingles, the vaccine, and the paper that provides evidence that the vaccine causes a reduced risk of dementia.

All about shingles and the shingles 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 remains hidden from the body’s immune system.

Even though the body develops an immune response to the original zoster virus infection, the adaptive immune response against the virus wanes or disappears several years or decades after the initial infection. 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 shingles 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 be given to individuals aged 19 or older with compromised immune systems. 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 at risk of shingles only if you have had chickenpox. Second, children who have received the chickenpox vaccine and never had chickenpox will not be at risk for shingles as they age.

Shingles vaccine reduces dementia risk paper

In a study published on 16 June 2026 in the Annals of Internal Medicine, Kaleen Hayes, PharmD, PhD, Brown University School of Public Health, Providence, Rhode Island, and co-authors followed 509,926 individuals, 66 years or older, who were admitted to a skilled-nursing facility between 1 January 2017 and 31 December 2022.

The researchers conducted a cohort study using target trial emulation, which uses observational data to mimic a randomized clinical trial. Participants were followed for up to 4 years until the outcome of dementia, Medicare disenrollment, or death.

Here are the key results:

• Individuals who received the recombinant shingles vaccine (Shingrix) had a 24% lower risk of dementia diagnosis over 4 years compared with those not vaccinated.
• Receiving at least one zoster shot was tied to a cumulative 4-year dementia risk that was 5.81 percentage points lower, 18.8% versus 24.6% with no vaccine.

The researchers concluded:

Receipt of RZV (recombinant zoster vaccine) during admission to a skilled-nursing facility or within 12 months was associated with lower dementia risk.

Summary

Once again, we have powerful evidence from a large cohort study that shows statistically lower risks of dementia in at-risk seniors after receiving the recombinant shingles vaccine. If you had any doubts about getting the vaccine, if you are a senior, this should obliterate them.

There are some cautions about this data. There may be some confounders that may have influenced the data. Also, individuals who received the vaccine may lead healthier lifestyles or have better healthcare, thereby reducing the risk of dementia.

Once again, I need to caution the reader that almost no one thinks that the vaccine itself is linked to some unknown mechanism to reduce the risk of shingles. Instead, it is hypothesized that preventing shingles, which causes neuroinflammation and increases the risk of stroke, is the key mechanism. Also, vaccination in general may activate a robust immune response, which protects against the development of dementia and Alzheimer’s disease.

Get the shingles vaccine.

Citations

• Hayes KN, Harris DA, McConeghy KW, Grove LR, Joshi R, Han L, Davidson HE, Chachlani P, Bayer TA, Singh M, Abul Y, DeVone F, Gravenstein S. Dementia Risk After Recombinant Herpes Zoster Vaccination in Older Adults With a Recent Skilled-Nursing Facility Stay : A Target Trial Emulation. Ann Intern Med. 2026 Jun 16. doi: 10.7326/ANNALS-25-04689. Epub ahead of print. PMID: 42296498.
• Matthews AA, Danaei G, Islam N, Kurth T. Target trial emulation: applying principles of randomised trials to observational studies. BMJ. 2022 Aug 30;378:e071108. doi: 10.1136/bmj-2022-071108. PMID: 36041749.

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