HZ Vaccination Associated With Reduced Risk of Dementia Diagnosis

Background: Neuroinflammation and immune dysregulation have been implicated in the development of Alzheimer disease, and neurotropic herpesviruses affect the central nervous system. Herpesviruses can cause β-amyloid deposition in mice and “increase tau phosphorylation in human brain organoids and neuronal cell cultures.” Objective: To investigate whether herpes zoster (HZ) vaccination might reduce the risk of developing dementia. Design: Observational “natural” experiments in Canada. Participants/Methods: On September 15, 2016, a publicly funded dose of live-attenuated HZ vaccine was offered to Ontario residents aged 65 to 70 years, which resulted in a 27.4% increase in those vaccinated. This created 2 cohorts including those ineligible (born before January 1, 1946) and those eligible (born between January 1, 1946, and September 15, 1951). The primary outcome was a new diagnosis of any type of dementia during the 5.5-year follow-up. Data were derived from more...