A recent study indicates that administering the recombinant zoster vaccine (RZV), which protects against shingles (herpes zoster), within a year of a resident’s admission to or discharge from a US nursing home significantly reduces their risk of receiving a dementia diagnosis for up to four years.
Published in the Annals of Internal Medicine, this research corroborates earlier observational findings suggesting a similar protective effect. While prior investigations focused on an older version of the shingles vaccine, this study aimed to determine if RZV offered comparable benefits. The findings show that receiving a dose of RZV was linked to a 5.8-percentage-point decrease in the likelihood of a dementia diagnosis over a four-year period.
According to lead author Kaley Hayes, PharmD, PhD, from Brown University’s School of Public Health, this translates to a potential prevention of approximately one in 17 dementia cases through vaccination. Hayes noted that these results, while surprising, align with previous studies that primarily examined the earlier vaccine formulation.
Focus on an Under-researched Group
The researchers employed a target emulation trial methodology, utilizing Medicare and electronic health records of individuals aged 66 and older who were admitted to nursing homes between January 2017 and December 2022. This approach allowed for a simulation akin to a randomized controlled trial.
The core question investigated was whether receiving an RZV dose within a year of a significant health event would influence dementia risk. The study encompassed 509,926 individuals across 5,550 skilled nursing facilities, with their medical records analyzed for up to four years post-discharge. Participants who had passed away or already had a dementia diagnosis were excluded. Among the remaining cohort, 8,843 individuals (1.73%) received at least one RZV dose within a year of discharge, with the majority (87%) being vaccinated after leaving the facility. A control group of 259,518 individuals did not receive the vaccine.
Over the four years following vaccination, those who received RZV exhibited a 24% lower risk of dementia compared to their unvaccinated counterparts (a relative risk reduction of 5.8 percentage points).