Reduced risk of dementia with recombinant zoster vaccine in US adults age 65 or older.

INTRODUCTION: Herpes zoster vaccines may lower the risk of dementia onset. We evaluated new-onset dementia among US Medicare beneficiaries ≥65 years old following recombinant zoster vaccination (RZV). METHODS: We matched one RZV-exposed to two RZV-unvaccinated on age, sex, and race/ethnicity. Individuals were ≥65 years old on the RZV dose 2 date (RZV-exposed) or preventive care visit date (RZV-unvaccinated), enrolled in Medicare ≥11 months before this date, and had no pre-existing dementia of any type. Weighted Cox proportional hazards models generated hazard ratios (HR) of new-onset dementia, Alzheimer's disease (AD), and vascular dementia (VD). RESULTS: The incidence per 1000 person-years of new-onset dementia for 15,061/502,845 RZV-exposed and 36,526/1,005,690 RZV-unvaccinated was 10.45 and 15.73, respectively. Time-dependent HRs (95% confidence interval) for ≤3 and >3 years' follow-up were as follows: 0.67 (0.65, 0.68); 0.74 (0.69, 0.79) for dementia; 0.72 (0.69, 0.74); 0.83 (0.74, 0.94) for AD; 0.67 (0.64, 0.70); 0.66 (0.57, 0.78) for VD. DISCUSSION: Two-dose RZV may lower new-onset dementia, AD, and VD risk.