Overview
- A Cell report finds that among more than 14,000 Welsh seniors already diagnosed with dementia, receipt of Merck's Zostavax was associated with nearly a 30‑percentage‑point lower risk of dying from dementia over nine years.
- Earlier Wales data published in Nature showed about a 20% lower incidence of dementia over seven years among vaccinated adults compared with similar unvaccinated peers.
- Researchers say they have observed similar protective associations in linked health records from England, Australia, New Zealand and Canada.
- The mechanism remains unclear, with hypotheses ranging from reduced varicella‑zoster reactivation in nervous tissue to broader immune stimulation.
- The evidence is observational and based on the older Zostavax vaccine, whose protection wanes, and it is unknown whether the newer Shingrix vaccine confers similar dementia‑related benefits.