Growing research suggests the shingles vaccine may offer broader health benefits beyond preventing herpes zoster, including a potential role in reducing dementia risk.
A new study published in The Lancet indicates that vaccination against shingles may reduce or delay dementia diagnoses among older adults, adding to emerging findings connecting the vaccine with improved cardiovascular outcomes and slower biological ageing.
The study analysed health records of nearly 230,000 adults in Ontario, Canada, born between 1930 and 1960 and registered with primary care providers. Researchers leveraged the province’s 2016 immunisation programme, which offered the single-dose live-attenuated herpes zoster vaccine, Zostavax, free to people aged 65–70.
Participants were grouped by eligibility based on birth cohorts, enabling researchers to compare outcomes between vaccinated and non-eligible populations.
According to lead author Pascal Geldsetzer of Stanford University, the design approximated conditions of a randomised trial by using policy-driven eligibility rather than voluntary vaccination status.
Findings showed that individuals eligible for the vaccine were less likely to receive a dementia diagnosis over a 5.5-year follow-up period, with risk about two percentage points lower. Reduced incidence was also observed compared with similar cohorts in Canadian provinces without comparable vaccination programmes.
Researchers said the results provide evidence consistent with a cause-and-effect relationship between shingles vaccination and dementia risk reduction, noting the effect appeared stronger among women — possibly reflecting differences in immune response or disease prevalence.
Independent experts urged caution in interpreting the findings. Neurologist Peter Gliebus described the results as promising but not definitive, suggesting the vaccine’s protective effect may stem from preventing viral reactivation linked to neuroinflammation or from broader immune-system benefits.
Family physician David Cutler noted limitations in applying the findings globally, highlighting that Zostavax has been largely replaced in some countries by newer vaccines such as Shingrix.
He also emphasised that established lifestyle and health interventions — including blood pressure control, physical activity, smoking avoidance, healthy diet and social engagement — remain critical in preventing cognitive decline.
While further research is required, the study adds to growing evidence that shingles vaccination may contribute to dementia prevention strategies, alongside its established role in reducing the risk and severity of shingles among older adults.
