New Evidence Suggests Shingles Vaccine May Protect Against Dementia

Recent research is strengthening the case that the shingles vaccine could lower the risk of developing dementia. A study published in the journal JAMA by a team at Stanford University analyzed the effects of the herpes zoster (HZ) vaccine, specifically Zostavax®, on dementia risk using data from a natural experiment conducted in Australia.

Earlier this month, a separate article based on patient data from Wales reported significant findings, indicating that the vaccine reduced the incidence of dementia. The study found that the likelihood of receiving a new dementia diagnosis decreased by 3.5 percentage points over a seven-year follow-up period after vaccination, representing a relative reduction of 20%.

The Australian study employed a similar methodology to that used in the Welsh study to evaluate the impact of the HZ vaccine on dementia occurrences in a different population and healthcare system. It analyzed primary care data from 101,219 patients across 65 Australian practices, with an average follow-up duration of 7.4 years.

In Australia, the rollout of the vaccine was subject to age eligibility criteria. Individuals born just before November 2, 1936, were over 80 and ineligible for the vaccine, while those born shortly after that date, aged between 70 and 79, were eligible. This slight age difference helped to minimize systematic biases, as no significant disparities in health or behavior were anticipated.

Vaccination rates among those eligible were notably higher than those over 80 years old, with 30.2% of the eligible group receiving the vaccine compared to only 6.5% of the older cohort. This difference resulted in a significant reduction in new dementia diagnoses by 1.8 percentage points. Additionally, the eligibility for vaccination did not appear to influence the prevalence of other chronic conditions or the utilization of additional preventive services.

These findings provide compelling evidence that vaccination against shingles could be a proactive measure in reducing the risk of dementia, potentially offering a dual benefit of preventing both shingles and cognitive decline as individuals age.