Exploring Shingles Vaccine Impact on Dementia Prevention in Wales

A recent shingles vaccine rollout in Wales was associated with about a 20% lower rate of dementia diagnoses over seven years among older adults.

Age-based eligibility created a natural experiment comparing near-identical cohorts. Vaccination corresponded to roughly a one-fifth lower dementia risk sustained across the follow-up period.

The association appeared larger in women, which could reflect sex-differential immune responses or sex patterns in dementia incidence.

Anchoring eligibility to a birthday cutoff reduced healthy‑user selection and approximated randomized allocation, strengthening causal inference relative to prior observational work. Remaining limitations include potential residual confounding, diagnostic misclassification, and uncertain generalizability outside Wales.