Herpes Zoster Vaccination Reduces Mild Cognitive Impairment Diagnoses and Deaths Due to Dementia

Using natural experiments, researchers previously reported that live-attenuated herpes zoster (HZ) vaccination appears to have prevented or delayed dementia diagnoses in both Wales and Australia.

In a new study published in the journal Cell on December 2, 2025, they report that HZ vaccination also reduces the diagnoses of mild cognitive impairment and, among patients living with dementia, decreases deaths due to dementia.

This exploratory analyses suggest that the effects are not limited to a specific type of dementia.

The study team wrote, 'Given that it is a readily available, relatively inexpensive, one-off, and safe intervention, the finding that HZ vaccination has a beneficial effect on the dementia disease process would be of great significance to population health, clinical medicine, and dementia research.'

'Our approach leverages the fact that individuals who turned eighty just after the start of the HZ vaccination program in Wales were eligible for the vaccine for one year, while those who turned eighty just before were ineligible and remained so for life.'

'A key strength of our natural experiments is that these comparison groups should be similar in all characteristics except for a small age difference.'

'Overall, our findings suggest that live-attenuated HZ vaccination not only prevents or delays mild cognitive impairment and dementia but also slows the progression of the disease among those already living with dementia.'

This study's approach avoids the common confounding concerns of observational data