Thrombosis with thrombocytopenia syndrome is a rare complication associated with COVID-19 vaccines.
Doctors use the term “thrombosis” to describe when a blood clot, or thrombus, forms and blocks a blood vessel. Sometimes this can
Thrombocytopenia is when a person has a low platelet count. Platelets are components in the blood that
This article reviews the symptoms, causes, risk factors, and treatment of thrombosis with thrombocytopenia syndrome related to COVID-19 vaccines. It also discusses when someone should speak with a doctor.
A note about sex and gender
Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.
Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a condition scientists first identified in
A person who develops the syndrome will have a blood clot along with an extremely low platelet count. While it is a rare side effect of COVID-19 vaccination, thrombosis with thrombocytopenia syndrome is a medical emergency, and people who develop it need rapid medical care.
Symptoms a person should be aware of and seek emergency medical attention for may include:
- chest pain
- headache that lasts for more than 48 hours after vaccination or appears later than 48 hours after vaccination and:
- may be accompanied by nausea and vomiting
- may be initially relieved by simple painkillers but then come back
- may worsen while lying down
- blurred vision
- seizures or confusion
- difficulty speaking
- trouble breathing
- tiny blood spots under the skin, also known as petechiae, not near the site of injection
- persistent abdominal pain
- swelling in the leg
According to the American Society of Hematology (ASH), people should seek immediate medical attention if any of the following symptoms develop 4–42 days after vaccination:
- shortness of breath
- severe headache
- visual changes
- back pain
- petechiae, easy bruising, or bleeding
- abdominal pain
- nausea and vomiting
- leg pain or swelling
However, the ASH also highlights that the incidence of this condition is extremely low, and the risk of death and severe outcomes of COVID-19 far outweigh the risk of VITT in relation to COVID-19 vaccines.
Common COVID-19 vaccine side effects
Common side effects of a COVID-19 vaccination are typically mild to moderate and may not occur in everyone.
Certain COVID-19 vaccinations can,
According to the ASH, both the Vaxzevria (AstraZeneca) and the Janssen (Johnson & Johnson) adenoviral COVID-19 vaccines are more likely to cause the syndrome than the Moderna or Pfizer mRNA vaccines.
Researchers first identified the syndrome in
According to the Melbourne Vaccine Education Centre, there are no clear diagnostic indicators for people who have a higher risk of developing thrombosis with thrombocytopenia syndrome.
It states that although people under 60 years old appear to be more at risk, there have also been cases in older adults. Some evidence also suggests the incidence may be higher in females. However, this may be because females have received more vaccine doses worldwide.
The center reports that there are currently no known medical conditions that may increase a person’s risk of developing the syndrome, including a history of blood clots.
Many healthcare organizations, such as the ASH and the
People should seek emergency medical treatment if they experience signs of the syndrome. Although it is a newly identified condition, specialists have identified treatments including:
- anticoagulant medications other than heparin
- intravenous immunoglobulin, which involves a healthcare professional administering an infusion of antibodies into a person’s bloodstream
- prednisolone, which is a type of corticosteroid
A person should seek emergency medical attention if they develop symptoms associated with thrombosis with thrombocytopenia syndrome. Early detection and diagnosis can help improve outcomes and prevent complications.
The risk of developing thrombosis with thrombocytopenia syndrome is very low. The benefits of COVID-19 vaccination outweigh the possible risk of developing this syndrome or other possible complications that rarely occur.
A person with concerns about the safety of COVID-19 vaccines may find speaking with a doctor about them useful. A healthcare professional can discuss the potential side effects and the benefits of vaccination in further detail. They may also recommend getting one type of COVID-19 vaccine over another.
Thrombosis with thrombocytopenia syndrome is a rare complication that may occur following COVID-19 vaccination. The condition causes a person to develop a potentially life threatening blood clot and a low blood platelet count.
A person with the syndrome may present with several different symptoms, including trouble breathing, persistent headache, blurred vision, among others. People with any signs of thrombosis with thrombocytopenia syndrome should seek emergency medical attention by calling 911 as soon as possible.
Many health organizations state that the benefits of COVID-19 vaccinations outweigh the potential risk of developing thrombosis with thrombocytopenia syndrome or any other possible complications.