Herpes Zoster Vaccination and Dementia Occurrence

Recent evidence from a quasi-experiment in Wales showed that herpes zoster (HZ) vaccination appears to prevent or delay dementia. Exploiting a similar quasi-experiment in Australia, this study investigated the effect of HZ vaccination on dementia occurrence in a different population and health system setting.

To determine the effect of HZ vaccination on the probability of receiving a new diagnosis of dementia. Design, Setting, and Participants: In Australia, starting November 1, 2016, live attenuated HZ vaccination was provided free to individuals aged 70 to 79 years through primary care clinicians. Thus, individuals whose 80th birthday was just a few weeks before November 1, 2016, never became eligible, whereas those whose 80th birthday was just a few weeks later were eligible. The key strength of this quasi-experiment is that one would not expect that these comparison groups who differ in age only minutely would, on average, differ in any health characteristics and behaviors. Primary health care records were analyzed with week-of-birth information from 65 general practices across Australia, using a regression discontinuity design. Exposure: Eligibility for HZ vaccination based on date of birth. Main Outcome: New diagnoses of dementia as recorded in primary care electronic health record data.