Shingles Vaccine Linked to Reduced Dementia Risk, New Research Confirms

New research published in The Lancet Neurology (2026, DOI: 10.1016/S1474-4422(25)00455-7) provides further evidence that the shingles vaccine may reduce the risk of dementia and potentially slow its progression. The findings corroborate previous studies published in Nature (2025, DOI: 10.1038/s41586-025-08800-x) and Clinical Infectious Diseases (2021, DOI: 10.1093/cid/ciaa014).

How the Research Was Conducted

Researchers examined the impact of introducing a herpes zoster (shingles) vaccination program in Ontario, Canada. Eligibility for the vaccine was determined by birthdate: individuals who turned 71 after January 1, 2017, were eligible, whereas those who turned 71 before that date were not.

Key Findings: A 20% Reduction in Dementia Risk

The studies consistently demonstrate a significant association between shingles vaccination and a reduced risk of dementia. Analysis of health records from Welsh older adults revealed that those who received the shingles vaccine were 20% less likely to develop dementia over a seven-year period [1]. A similar analysis of data from Ontario, Canada, confirmed these results.

The Virus-Dementia Connection

These findings support a growing theory that viruses affecting the nervous system may contribute to dementia risk [1]. Shingles is caused by the varicella-zoster virus, the same virus that causes chickenpox. After a chickenpox infection, the virus remains dormant in nerve cells for life. Reactivation of the virus can lead to shingles, particularly in older adults or those with weakened immune systems.

Potential Benefits for Those Already Diagnosed

The research suggests the shingles vaccine may not only prevent dementia but too slow its progression in individuals already diagnosed with the condition [1]. A study published in Cell found evidence supporting this potential benefit.

Blood-Based Biomarker Research

Further investigation is underway to understand the mechanisms behind this protective effect. Researchers are analyzing blood samples collected during a past shingles vaccination trial to identify biomarkers associated with dementia [3]. The goal is to determine how the vaccine impacts these biomarkers and potentially identify new targets for dementia prevention, and treatment.

Study Design: A Natural Experiment

The research utilized a “natural experiment” approach, taking advantage of the birthdate-based eligibility criteria for the shingles vaccine in Wales [2]. By comparing individuals born just before and after the eligibility cutoff date, researchers were able to isolate the effect of the vaccine, minimizing the influence of other factors.

Looking Ahead

While these findings are promising, further research, including clinical trials, is needed to confirm the benefits of shingles vaccination for dementia prevention and treatment. However, the current evidence suggests that this readily available vaccine could represent a valuable tool in the fight against this devastating disease.