A new follow-up study has found that the shingles vaccine – which had been found in an earlier study to slow the progression of dementia in those already diagnosed – is also linked to reduced cases of death by dementia in patients with an existing diagnosis.
The shingles vaccination programme that began in Wales in 2013 had led to two discoveries that give fresh hope to efforts to treat dementia: the vaccine appears to reduce the risk of mild cognitive impairment, as well as slowing progression of dementia in those already diagnosed, reports ScienceAlert.
Earlier this year, (April,) findings on the discovery that the vaccine may help prevent dementia were published in Nature.
The latest study, from an international team of scientists, adds to a growing body of evidence that stopping viruses that affect the nervous system – such as the varicella zoster virus, which causes shingles – could also protect against dementia.
“Because the vaccine is safe, affordable, and already widely available, this finding could have major implications for public health,” said epidemiologist Haroon Ahmed, from Cardiff University.
“More research is needed to test our work and understand more about the potential protective effect the vaccine offers against dementia, particularly how and why it works.”
The Welsh vaccination programme rolled out more than a decade ago by the UK National Health Service gave researchers the opportunity to analyse a randomised clinical trial, without actually running one: to ration vaccines, those aged 79 could get it, while those aged 80 couldn’t.
That quirk meant that the effects of the vaccine could be studied in two very similar groups, with an age difference of just one year between them. It goes a long way to reducing the influence of other factors that play into dementia risk, such as education level or other medical conditions.
Of the 14 350 people diagnosed with dementia before the start of the vaccine programme, about half died of the condition within nine years. Being vaccinated against shingles made this nearly 30% less likely, according to the analysis, suggesting a significant level of protection.
The researchers also found that the vaccinated participants were less likely or slower to develop mild cognitive impairment, a common precursor to dementia. Combined with the earlier findings that the vaccine reduced the risk of dementia starting at all, these are encouraging signs.
“The most exciting part is that this really suggests the shingles vaccine doesn’t have only preventive, delaying benefits for dementia, but also therapeutic potential for those who already have dementia,” says biomedical scientist Pascal Geldsetzer from Stanford University in the United States.
Even with the serendipitous design of the Welsh vaccination programme, the data aren’t robust enough to show direct cause and effect – but they do show a significant connection that’s worth investigating further.
One of the next challenges is going to be figuring out why the shingles vaccine might be having this impact on dementia development and diagnosis. There might be nervous system or immune system mechanisms at play – viruses affecting the nervous system have been linked in animal models to the toxic protein build-up seen with Alzheimer’s, for example.
Further studies could potentially look at larger groups of people across a wider range of ages, as well as investigating the latest shingles vaccine: the vaccine used in Wales in 2013 has since been retired for a new and improved version.
“At least investing a subset of our resources into investigating these pathways could lead to breakthroughs in terms of treatment and prevention,” said Geldsetzer.
The research was published in Cell.
Study details
The effect of shingles vaccination at different stages of the dementia disease course
Min Xie, Markus Eyting, Christian Bommer, Haroon Ahmed, Pascal Geldsetzer.
Published in Cell on 2 December 2025
Highlights
Herpes zoster vaccination reduced dementia diagnosis in our prior natural experiments
Here, we find a lower occurrence of MCI and dementia deaths among dementia patients
Herpes zoster vaccination appears to act along the entire clinical course of dementia
This study’s approach avoids the common confounding concerns of observational data
Summary
Using natural experiments, we have previously reported that live-attenuated herpes zoster (HZ) vaccination appears to have prevented or delayed dementia diagnoses in both Wales and Australia. Here, we find that HZ vaccination also reduces mild cognitive impairment diagnoses and, among patients living with dementia, deaths due to dementia. Exploratory analyses suggest that the effects are not driven by a specific dementia type. Our approach takes advantage of the fact that individuals who had their eightieth birthday just after the start date of the HZ vaccination program in Wales were eligible for the vaccine for 1 year, whereas those who had their eightieth birthday just before were ineligible and remained ineligible for life. The key strength of our natural experiments is that these comparison groups should be similar in all characteristics except for a minute difference in age. Our findings suggest that live-attenuated HZ vaccination prevents or delays mild cognitive impairment and dementia and slows the disease course among those already living with dementia.
See more from MedicalBrief archives:
Shingles jab slashes CVD events, dementia – US study
Shingles jab may cut heart attack, stroke risk – global review