A new study published in Neurology found that adults 65 and older who received the high-dose influenza vaccine had a 15% to 20% lower risk of developing Alzheimer’s disease over approximately two years compared to those who received the standard-dose vaccine.
The research, led by Dr. Paul Schulz of UTHealth Houston, analyzed data from about 165,000 older adults vaccinated between 2014 and 2019, with roughly 121,000 receiving the high-dose formulation and 44,000 the standard dose. Participants were followed for an average of three years post-vaccination.
This builds on Schulz’s 2022 study, which linked annual flu vaccination to up to a 40% reduction in Alzheimer’s risk over six years. However, that earlier work raised concerns about the “healthy vaccinee effect” — the possibility that vaccinated individuals simply lead healthier lifestyles overall.
To address this, the current study focused exclusively on vaccinated individuals, comparing high-dose versus standard-dose recipients to isolate the impact of vaccine strength. Schulz noted the idea emerged after a public health department query about whether a dose-dependent protective effect existed.
The high-dose flu vaccine, which contains four times the antigen of the standard version, is already recommended by the CDC for all adults 65 and older due to age-related immune decline. This proves widely available through pharmacies and health departments, though supply can occasionally be limited.
For more on this story, see High-Dose Flu Vaccine Linked to Lower Alzheimer’s Risk in Seniors.
Schulz suggested the protective effect may stem not just from flu prevention but from a broader immunomodulatory response — the act of generating antibodies might influence inflammatory processes in the brain. “The vaccination turns on your ability to make antibodies against the virus. But we think as a side effect, the activity in the arm has a modulating effect on the brain, on inflammatory cells,” he told the San Francisco Chronicle.
This aligns with growing evidence that other vaccines, particularly the shingles vaccine, may also reduce dementia risk. A Stanford-led study published in 2025 found older adults who received the shingles vaccine were 20% less likely to develop dementia over seven years, potentially by reducing neuroinflammation linked to both shingles and Alzheimer’s pathology.
Experts caution that while the findings are promising, it is too soon to recommend the high-dose flu vaccine solely for Alzheimer’s prevention. The observed associations do not prove causation, and further research is needed to understand the biological mechanisms involved.
This follows our earlier report, High-Dose Influenza Vaccine Reduces Hospitalizations in Adults 65+.
Does getting the high-dose flu shot guarantee I won’t develop Alzheimer’s?
No. The study shows an association between high-dose vaccination and reduced risk, not prevention. Many factors influence Alzheimer’s development, and the vaccine should be viewed as one potential protective measure among others, not a guarantee.
Should I ask for the high-dose flu vaccine specifically if I’m over 65?
Yes. The CDC already recommends the high-dose flu vaccine for all adults 65 and older due to its superior protection against influenza. If you are in this age group, Consider receive it unless contraindicated, and discuss availability with your provider or pharmacist.
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