Recent observational studies suggest that routine vaccinations may be associated with a reduced risk of developing dementia and Alzheimer’s disease.
These findings are significant because they suggest that common preventative healthcare measures could offer secondary neurological protections for an aging global population.
In the U.S., a study of more than 200,000 older adults [2] found that the high-dose flu vaccine was associated with a 55% lower risk of developing Alzheimer’s disease [1]. Researchers also examined other routine vaccinations, including Tdap, pneumococcal, and hepatitis vaccines, finding a general observational association with lower dementia risk [5].
Separate research conducted in Wales, United Kingdom, focused on a cohort of more than 280,000 older adults [4]. That analysis indicated that the shingles vaccine was linked to a 20% reduction in dementia risk [3].
Scientists hypothesize that these benefits result from a process called trained immunity. According to this theory, vaccines train the innate immune system to respond more effectively, which may reduce the neuroinflammation that contributes to the progression of dementia [5].
"Getting your annual flu shot may come with a significant side benefit: helping to protect you from dementia," Dana G. Smith said in April 2026.
“High-dose flu vaccine associated with 55% lower risk of developing Alzheimer’s disease”
While these studies show a strong correlation between vaccination and cognitive health, they remain observational. This means they identify a relationship but do not prove that vaccines directly cause the reduction in dementia. Further clinical trials are necessary to determine if 'trained immunity' is the definitive mechanism and if these vaccines can be used as a formal preventative strategy against neurodegenerative diseases.
