Another possible vaccine benefit: Seasonal flu shot linked to a reduced risk of Alzheimer's, study finds

Your annual flu shot may have other long-term benefits aside from protecting against the virus. 

A new study found the seasonal influenza vaccine was linked with a reduced risk of Alzheimer's disease, researchers at the Alzheimer's Association International Conference revealed Monday. 

In the study, at least one flu vaccination was associated with a 17% reduction in Alzheimer's. Additionally, more frequent flu vaccinations were associated with another 13% reduction.

“Our study suggests that regular use of a very accessible and relatively cheap intervention – the flu shot – may significantly reduce risk of Alzheimer’s dementia,” said Albert Amran, a medical student at the McGovern Medical School at the University of Texas Health Science Center who was involved in the study.

Researchers also found the protective association between the vaccine and the risk of Alzheimer’s was strongest for those who received their first vaccine at a younger age. For example, those who go their first documented flu shot at age 60 benefited more than those who first received it at 70.

While the study doesn’t explain why flu vaccinations are linked to a reduced risk of Alzheimer’s disease, some experts speculate the vaccine may affect brain inflammation that could lead to the disease, said Dr. Steven DeKosky, professor of neurology at the University of Florida and deputy director of UF’s McKnight Brain Institute.

“The vaccine activates the immune system to defeat the flu virus itself,” he said. “The activation may have beneficial effects that fight off or slow down the inflammation associated with AD.”  

However, the Mayo Clinic says most scientists believe Alzheimer's disease is caused by a combination of genetic, lifestyle and environmental factors that affect the brain over time.

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“People like to argue that people who are more likely to get regular vaccinations are those that have regular primary care and are perhaps more likely to get preventive health interventions,” said Dr. Zaldy Tan, medical director at the University of California-Los Angeles Alzheimer’s and Dementia Care Program.

The findings add to the growing evidence of vaccination benefits as scientists work doubletime to create a coronavirus vaccine by 2021 – which only about half of Americans say they would get, according to a poll in May from The Associated Press-NORC Center for Public Affairs Research.

“With the COVID-19 pandemic, vaccines are at the forefront of public health discussion,” said Mari Carrillo, Alzheimer’s Association chief science officer. “It is important to explore their benefit in not only protecting against viral or bacterial infection but also improving long-term health outcomes.”

While people are hunkered down in their homes and are less likely to spread the seasonal flu, some experts are worried they also are less likely to get the annual vaccine. Before the pandemic, many Americans enjoyed the convenience of receiving their shot at the office. 

Experts hope people are proactive about visiting their local pharmacy or family doctor to get their flu shot this year, especially with flu season around the corner and coronavirus cases on the rise. Many worry both viruses could overwhelm hospitals in the fall. 

“(The study) is another good reason to get your flu shot and prevent that chaos from happening,” said DeKosky.

Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT. 

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