Does the Shingles Vaccine Reduce the Risk of Alzheimer’s and Dementia?

The shingles vaccine is given to protect against painful shingles. Could the same vaccine also reduce the likelihood of developing dementia later in life?

Research published in recent years has brought this question to the attention of scientists. In particular, the approximately 20% lower probability of a dementia diagnosis reported in a study in Wales attracted the interest of many people over 50. Nature, 2025

Current evidence suggests a promising possible additional benefit. However, the shingles vaccine has not yet been shown to definitively prevent Alzheimer’s disease or treat dementia. Its established purpose is to prevent shingles and the long-lasting nerve pain that can follow it. Current evidence review, European Medicines Agency

How might shingles and dementia be linked?

Shingles develops when the varicella-zoster virus, which also causes chickenpox, reactivates. After chickenpox, the virus can remain dormant in nerve tissue and reactivate with increasing age or weakened immunity. European Medicines Agency

Researchers think that viral reactivation may contribute to processes that affect brain health in some people. Possible pathways include effects on blood vessels in the brain and inflammatory responses in the nervous system.

However, studies examining shingles and subsequent dementia have not produced entirely consistent results. The effects of age, other illnesses and overall health are difficult to separate. Therefore, having shingles does not mean that a person will develop Alzheimer’s disease. Review of VZV and dementia, 2026

Are Alzheimer’s disease and dementia the same?

Dementia is a syndrome affecting memory, thinking and the ability to carry out everyday tasks, and can be caused by different diseases. Alzheimer’s disease is its most common cause. Other forms include vascular dementia. World Health Organization

This distinction matters when interpreting news about shingles vaccination. A decrease in overall dementia diagnoses does not demonstrate that Alzheimer’s disease has been prevented to the same extent.

What does “20% lower risk” in the Welsh study mean?

The study, published in Nature in 2025, used the birth-date eligibility rule of the Welsh vaccination programme. People of almost identical ages on either side of the eligibility threshold were compared.

The researchers estimated that receiving the live shingles vaccine reduced the probability of a new dementia diagnosis over seven years by approximately 20% in relative terms. The absolute difference was 3.5 percentage points. This does not mean that “20 out of every 100 people are protected against dementia.” Welsh study

This approach aims to reduce differences that can influence comparisons, such as vaccinated people taking greater care of their health. Nevertheless, the findings must be interpreted within the assumptions of the method, the accuracy of health records and the age group studied.

Is there also evidence for the recombinant shingles vaccine used today?

Yes. Dementia research is not limited to the older live vaccine.

A study published in Nature Medicine in 2024 compared recipients of the recombinant vaccine with recipients of the live shingles vaccine. The recombinant vaccine was associated with more favourable dementia outcomes over six years. The reported “17% increase in diagnosis-free time” is not the same as a “17% reduction in dementia risk”; it represents a different statistical measure. Taquet and colleagues, 2024

Research published in Nature Communications in 2026 compared 65,800 adults aged 65 and over who received two doses of recombinant vaccine with 263,200 unvaccinated people. Vaccination was associated with less dementia. However, the association became smaller when the comparison group consisted of recipients of another vaccine. This suggests that general health behaviours among vaccinated people may also affect the results. Rayens and colleagues, 2026

These studies support a possible benefit. However, differences in vaccine types, age groups and comparison methods mean that a single protective-effect percentage cannot be given.

Why are scientists still cautious?

Vaccinated and unvaccinated people may differ in access to healthcare, preventive health habits and other illnesses. Statistical adjustments can reduce these differences but may not eliminate them.

A systematic review and meta-analysis published in 2026 found strong evidence supporting protection by recombinant shingles vaccination against shingles, but rated the certainty of evidence for a possible reduction in dementia risk as low. This does not mean there is no association; it means the true effect may differ substantially from current estimates. Systematic review, 2026

Another analysis published that year questioned how much of the findings from some natural experiments could be attributed to vaccination and emphasised the need for independent confirmation. Kivimäki and colleagues, 2026

Fewer dementia diagnoses in health records alone cannot distinguish between complete prevention, delayed clinical symptoms and changes in the timing of diagnosis. Evidence and mechanisms review, 2026

How might shingles vaccination affect brain health?

Three main possible explanations are being investigated:

• Reduced viral reactivation: limiting possible damage from repeated viral activity.
• Effects on vascular and inflammatory processes: reducing inflammatory responses in brain blood vessels and nerve tissue.
• Changes in immune responses: effects on the immune system beyond protection against the virus.

These mechanisms remain under investigation. It is not yet clear which pathway explains a possible dementia benefit in humans, or to what extent. There is insufficient evidence to say that shingles vaccination prevents Alzheimer’s by suppressing inflammation in the brain. Review of mechanisms, 2026

What do these findings mean for people over 50?

For adults aged 50 and over, the main reason to consider shingles vaccination is protection against shingles and the long-lasting nerve pain that may follow it. The recombinant vaccine is authorised for this age group. It also has indications for younger adults at increased risk of shingles. European Medicines Agency

Dementia research adds an interesting possible additional benefit. However, we cannot currently say with certainty how vaccination at age 50 changes an individual’s future dementia risk. The Welsh findings in people around age 80 should not be applied at the same percentage to every age group.

Vaccination decisions should be made with a doctor, taking account of age, immune status, treatments, previous vaccines and allergy history. Administration is planned according to current product information and relevant recommendations.

Frequently asked questions about shingles vaccination

Does the shingles vaccine prevent Alzheimer’s disease?

Definitive prevention has not been established. Studies report a promising association between vaccination and lower dementia risk. The Alzheimer’s-specific effect and the true level of protection remain uncertain. Current systematic review

How many doses are needed?

The recombinant shingles vaccine is given in two doses, usually 2–6 months apart. A shorter interval may be chosen for some immunocompromised people; a doctor determines the appropriate schedule. CDC vaccination recommendations

Can someone who has already had shingles be vaccinated?

A previous episode of shingles does not remove the need to assess vaccination. However, the vaccine is not given during an acute shingles episode. Timing should be planned with a doctor. CDC vaccination recommendations

What are the side effects?

Pain, redness or swelling at the injection site, fatigue, muscle pain, headache and fever can occur. Most of these common reactions last 2–3 days. Allergy history and individual health should be assessed before vaccination. European Medicines Agency

Is shingles vaccination used to treat someone with dementia?

Shingles vaccination cannot be recommended as dementia treatment. In someone already diagnosed with dementia, suitability is assessed for the purpose of shingles prevention and in the context of their overall health. Findings about different stages of the disease should not be presented as a proven treatment effect. Research on different disease stages, Vaccine indication

Other steps for brain health still matter

While shingles-vaccine research continues, physical activity, avoiding smoking, controlling blood pressure and diabetes, a healthy diet and social engagement remain important for brain health. World Health Organization

If you are aged 50 or over, you can discuss with your doctor whether shingles vaccination is suitable for you. You can consider its established benefits alongside the possible additional dementia benefit that remains under investigation.

This article provides general information and does not replace individual diagnosis, treatment or vaccination advice. Literature review date: 6 November 2026.