There is conflicting evidence around the theory that certain COVID-19 vaccines might increase the risk of stroke. However, the likelihood of stroke may be higher in unvaccinated people who develop COVID-19.
Therefore, the benefits of the vaccine outweigh the risk of stroke.
This article summarizes what scientists currently know about COVID-19 vaccines and the risk of stroke.
It discusses whether these vaccines are risk factors for stroke and whether they are safe for people who have already had a stroke. It also provides information about the signs of stroke.
All data and statistics are based on publicly available data at the time of publication. Some information may be out of date. Visit our coronavirus hub for the most recent information on COVID-19.
Scientists are unsure about the link between COVID-19 vaccines and the risk of stroke.
According to the
- Ischemic stroke: These strokes occur when there is a decreased blood supply to a part of the brain. This can happen when brain arteries gradually narrow, decreasing blood flow. These can also occur when a blood clot suddenly and completely blocks an artery.
- Hemorrhagic stroke: These strokes occur when a blood vessel bursts within the brain. Blood leaks out, depriving brain cells downstream of oxygen and nutrients. This blood leak can also send toxic chemicals into the surrounding cells and increase pressure within the skull. These processes may further harm brain cells.
Why might the vaccine increase stroke risk?
Because there are so many unknowns, it is difficult to speculate about what might explain any connection between COVID-19 vaccines and the likelihood of stroke.
- blood clotting
- high blood pressure
- low platelet counts
However, such risk factors were also more common in those who have COVID-19 than in the general population.
According to the above
In addition, the
Therefore, the risk of stroke may actually be higher among unvaccinated individuals who develop COVID-19 than in people who receive the vaccine.
When strokes cause brain cells to die, this process can result in various neurological symptoms. According to the
- sudden confusion
- sudden speaking difficulties, or difficulties understanding speech
- sudden weakness or numbness in the arm, face, or leg, which may affect only one side of the body
- sudden vision problems, in one eye or both, such as double vision
- sudden dizziness
- sudden loss of balance, coordination,
- sudden difficulties walking
- sudden severe headache
A stroke is a serious medical emergency. If an individual experiences these symptoms or notices that someone else has them, they must call emergency services right away.
Strokes are potentially life threatening conditions where not enough blood reaches a person’s brain. These health events can kill off brain cells.
There is some evidence that certain COVID-19 vaccines can increase risk factors for stroke. These risk factors include blood clots, high blood pressure, and low platelet counts. However, scientists remain unsure whether this translates into an elevated risk of stroke.
While early studies suggested some vaccines might have this effect, several vaccines never appeared to affect the risk of stroke. Furthermore, more recent studies have failed to discover robust links between COVID-19 and stroke risk. Scientists continue to study this topic.
Many doctors and scientists believe that, on balance, receiving these vaccines is less dangerous than not. This is true of people who have already had a stroke, as well as the general population.