A recent study of more than 280,000 people in Wales found the live-attenuated varicella zoster virus vaccine (Zostavax) reduced their risk of a new dementia diagnosis by 20% over a seven-year period. 

Published in Nature, the study is based on adults born between September 1925 and September 1942 who are registered with a primary healthcare provider (more than 98% of adults in Wales) and who had no dementia diagnosis at the start of the vaccine programme.  

Taking advantage of the unique way the shingles immunisation programme was rolled out in Wales in 2013 and examining other sources of bias, authors said the study provides evidence that is more likely to be causal than the existing, exclusively associational, evidence on this topic. 

“Our substantial effect sizes, combined with the relatively low cost of the zoster vaccine, imply that, if these findings are truly causal, the zoster vaccine will be both far more effective as well as cost-effective in preventing or delaying dementia than existing pharmaceutical interventions,” they wrote.  

When researchers compared new dementia diagnoses between the vaccine-eligible and ineligible populations, they also found the protective effect was stronger among women than men. 

In New Zealand, Shingrix, which is proven to be more effective than Zostavax, is funded for individuals at the age of 65 years and immunocompromised individuals aged 18 years or older who are at increased risk of herpes zoster. For others, immunisation costs between $600 to $800.