Blood clots are an extremely rare but serious side effect of AstraZeneca’s COVID-19 vaccine, regulators announced on Wednesday.
The benefits of the AstraZeneca vaccine still outweigh the risks, the European Medicines Agency (EMA) said in a press release. However, the agency’s safety committee said it was important to know the signs of a possible clot.
A blood clot occurs when the blood thickens and forms a semi-solid mass. It can be a helpful response to stop bleeding in the event of an injury, but these blockages can cause problems if they cut off blood flow to an important area.
Blood clots can cause blockages in the legs, abdomen and lungs. Most blood clots associated with the AstraZeneca vaccine have been found in veins in humans’ brains.
These blood clots, known as cerebral venous sinus thrombosis (CVST), can lead to stroke, seizures and death.
To date, most blood clots have occurred within two weeks of vaccination in women under 60 years of age.
As young people are more likely to experience this side effect, UK vaccine regulators recommend that people under 30 not get the AstraZeneca chance unless they have already received their first dose.
Blood clot symptoms include shortness of breath and headache
The EMA said patients receiving the AstraZeneca vaccine should seek immediate medical attention if they have the following symptoms:
- short of breath
- chest pain
- swelling in your leg
- persistent abdominal pain
- neurological symptoms, including severe and persistent headache or blurred vision
Some mild side effects, such as injection site pain or other body aches, are common in the days after vaccination.
However, if you experience severe or persistent symptoms about four to 20 days after vaccination, you should seek medical help, according to the World Health Organization.
Blood clots are usually treated with anticoagulants. Complications can be avoided if the blood clot is caught early.
This article was originally published by Business Insider.
More from Business Insider: