Covid Shots May Slightly Raise Stroke Risk
A recent study published in the New England Journal of Medicine has found a small but statistically significant association between Covid-19 vaccination and ischemic stroke, a type of stroke caused by a blood clot in the brain. The study analyzed data from more than 2.5 million people who received either the Pfizer-BioNTech or the Moderna mRNA vaccines in Israel between December 2020 and May 2021. The researchers compared the incidence of ischemic stroke in the first week after vaccination with the incidence in the same individuals during a control period of 14 days before vaccination. They found that the risk of ischemic stroke was increased by 1.6 per 100,000 person-years in the first week after vaccination, which translates to about 11 extra cases of stroke per million vaccinated people. The increased risk was mainly observed in people aged 50 years or older, and was similar for both vaccine types.
The authors of the study emphasized that the absolute risk of ischemic stroke after Covid-19 vaccination is very low, and that the benefits of vaccination outweigh the potential harms. They also noted that Covid-19 infection itself is a much stronger risk factor for stroke than vaccination, and that previous studies have shown that Covid-19 vaccines reduce the risk of severe infection and hospitalization. The study did not find any association between Covid-19 vaccination and hemorrhagic stroke, another type of stroke caused by bleeding in the brain.
The mechanism behind the possible link between Covid-19 vaccination and ischemic stroke is not clear, but the researchers speculated that it could be related to the activation of the immune system and inflammation, which may increase the tendency of blood to clot. They also suggested that some people may have underlying conditions that predispose them to stroke, and that vaccination may trigger or unmask these conditions. The researchers called for further studies to confirm their findings and to explore the causes and prevention of this rare adverse event.
What are the symptoms of stroke?
Stroke is a medical emergency that requires immediate attention. The symptoms of stroke depend on which part of the brain is affected, but they usually occur suddenly and can include:
- Weakness or numbness on one side of the body or face
- Difficulty speaking or understanding speech
- Confusion or loss of memory
- Vision problems or loss of sight in one or both eyes
- Dizziness, loss of balance, or difficulty walking
- Severe headache with no known cause
- Nausea or vomiting
If you or someone you know experiences any of these symptoms, call 911 or your local emergency number right away. Do not wait to see if the symptoms go away or improve. The sooner you get medical help, the better your chances of recovery and avoiding permanent disability.