Lancet Neurol

More evidence supports dementia‑delaying effect of zoster vaccination

January 27, 2026

In an analysis of natural experiments, investigators examined whether herpes zoster vaccination was associated with incident dementia in Canada. Using age‑based eligibility thresholds from the 2016 rollout of free shingles vaccination in Ontario and complementary quasi‑experimental methods across provinces, the study followed more than 230,000 older adults. Individuals just old enough to be eligible for vaccination had a significantly lower likelihood of a new dementia diagnosis over roughly five years of follow‑up compared with those just ineligible, with an absolute risk reduction of about 2 percentage points. Findings were consistent across multiple analytic approaches and provinces, strengthening the case for a potentially causal association.

Clinical takeaway: Live zoster vaccination in older adults appears to prevent or delay incident dementia, reinforcing its potential neuroprotective role.

Source:

Pomirchy M, et al. (2026, February). Lancet Neurol. Herpes zoster vaccination and incident dementia in Canada: an analysis of natural experiments. https://pubmed.ncbi.nlm.nih.gov/41579903/