Nov. 3, 2022

Flu vaccine lowers risk of stroke, research shows

UCalgary study discovers new benefit to annual influenza shot
Study shows flu vaccination lowers risk of stroke
Study shows flu vaccination lowers risk of stroke. Colourbox

Researchers at the University of Calgary say the flu vaccine lowers the risk of stroke among adults even if they are not at high risk for stroke. Investigators evaluated the health records of over four million Albertans over a nine-year period. The results indicate vaccination against influenza should be strongly recommended for everyone, just like it is for those with heart disease.

“The flu shot is known to reduce the risk of heart attack and hospitalization for people with heart disease. We wanted to find out whether the vaccine has the same protective qualities for those at risk of stroke,” says Dr. Michael Hill, MD, researcher at the Cumming School of Medicine (CSM) and principal investigator on the study.

Our findings show the risk of stroke is lower among people who have recently received a flu shot. This was true for all adults, not just those at high risk of having a stroke.

Data used in the study comes from the Alberta Health Care Insurance Plan. Researchers accounted for several factors including age, anticoagulant use, and risk factors including chronic health conditions.

“We found that the risk of stroke was significantly reduced in the six months following an influenza vaccination.,” says Dr. Jessalyn Holodinsky, PhD, assistant professor at the CSM and first author on the study.

“The findings suggest broad influenza vaccination may be a viable public health strategy to prevent stroke.”

Jessalyn Holodinsky, first author, Michael Hill, principal investigator

Researchers Jessalyn Holodinsky, left, and Michael Hill say the findings suggest broad influenza vaccination may be a viable public health strategy to prevent stroke.

Quentin Collier, Department of Clinical Neurosciences

The study is published in The Lancet Public Health. The researchers say two strengths of this study are that it used data from an entire population over a period of 10 flu seasons, and the study occurred in a province with one single universal health-care system.

Hill says the generalized benefit of influenza vaccination for stroke prevention is a new finding that he hopes will lead to more research about the indirect protective factors of the flu and other vaccines.

“We know that upper respiratory infections often precede heart attacks and strokes.  Preventing or reducing the severity of influenza provides a protective factor particularly for stroke,” says Hill.

“The protective association was very strong. We saw it benefited both men and women and that there was a clear reduction in risk of stroke with increasing age for those who had a flu shot.”

The study adds to the body of research conducted by the Calgary Stroke Program, a collaboration between the University of Calgary (Hotchkiss Brain Institute, Department of Clinical Neurosciences) and Alberta Health Services at the Foothills Medical Centre.

Michael Hill is a neurologist at the Foothills Medical Centre and a professor in the Cumming School of Medicine’s (CSM) departments of Clinical Neurosciences, Radiology, Medicine, and Community Health Sciences. He is a member of the Hotchkiss Brain Institute, the Libin Cardiovascular Institute and the O’Brien Institute for Public Health at the CSM. 

Jessalyn Holodinsky is an assistant professor in the departments of Emergency Medicine,  Clinical Neurosciences, and Community Health Sciences at the Cumming School of Medicine (CSM). She is a member of the O’Brien Institute for Public Health, Hotchkiss Brain Institute and the Alberta Children’s Hospital Research Institute at the CSM. 

The Hotchkiss Brain Institute
The Hotchkiss Brain Institute (HBI) at the University of Calgary consists of more than 140 scientists and clinician-scientists who are dedicated to advancing brain and mental health research and education. The institute’s research strengths, in Brain & Behaviour, Neural Injury & Repair and Healthy Brain Aging, are leading to a better understanding of the brain and nervous system and new treatments for neurological and mental health disorders, aimed at improving quality of life and patient care. Learn more about the HBI

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