New data shows COVID-19 vaccine does not raise stroke risk

Aug. 25, 2022
Cedars-Sinai experts say, however, that while COVID-19 vaccines don’t increase the risk of stroke, infection does.

Newly compiled data evaluated by researchers in the Department of Neurology and the Smidt Heart Institute at Cedars-Sinai shows that COVID-19 vaccines do not raise stroke risk—but that severe COVID-19 infection does. Physician-scientists hope this growing body of evidence, highlighted in an editorial in the peer-reviewed journal Neurology, will ease the minds of individuals still hesitant to be vaccinated.

“We now know that patients who've had a vaccine are not at higher risk of stroke, thanks to a large body of data with millions of patients who have been included,” said Alexis Simpkins, MD, PhD, director of Vascular Neurology Research in the Department of Neurology at Cedars-Sinai and co-author of the editorial and of a related study published by the journal. “You're 200 times less likely—if you compare the numbers—to have had a stroke if you were vaccinated, than a person who was hospitalized with severe COVID-19 and was not vaccinated.”

That’s because COVID-19 infection, especially severe infection, can cause inflammation, clot formation and heart disease that increase stroke risk, Simpkins said.

“Clots can form and block blood flow to the brain. The lack of blood flow causes the brain cells to die, resulting in an ischemic stroke. Also, COVID-19-related inflammation can damage blood vessels in the brain, disrupting blood vessel integrity and resulting in brain hemorrhage,” said Simpkins.

Cedars-Sinai release