Medically reviewed in April 2021
Updated on April 16, 2021
More than 7.7 million U.S. adults received the Johnson & Johnson COVID-19 vaccine as of April 15. Just two days earlier, federal health officials halted its use at federal sites and recommended that states do the same due to safety concerns involving a rare and serious type of blood clot.
Six women between the ages of 18 and 48 reportedly developed a very rare condition, known as cerebral venous sinus thrombosis (CVST), in combination with low levels of blood platelets (thrombocytopenia), 6 to 13 days after they received the J&J vaccine.
CVST occurs when a blood clot forms in the brain, which prevents blood from draining. This can increase pressure and cause blood cells to break and leak into the brain.
It’s very rare. It affects about five out of one million people each year. And even among those who’ve received the J&J shot, it remains a very rare event, according to the Centers for Disease Control and Prevention (CDC).
But if you’re one of the millions of adults who’ve gotten the J&J shot, you may still be wondering what this means for you.
What—if anything—should you do now?
When to seek medical attention
How long it’s been since you got your shot matters. So far, all reported cases of CVST occurred among people who had received the vaccine within the past two weeks.
Health officials advise those who’ve gotten the vaccine to be on the lookout for symptoms of the condition for three weeks afterwards. So, if you got your shot a month ago, you’re likely not at increased risk for this complication.
If you got your shot within the past three weeks, however, it’s important to recognize the following symptoms:
- Severe headache
- Backache
- Abdominal pain
- Leg pain
- Shortness of breath
- Tiny red spots on the skin (petechia)
- New or easy bruising
- Blurred vision
- Fainting or loss of consciousness
Anyone recently vaccinated against COVID-19 with the J&J shot who develops these symptoms should seek immediate medical attention.
More severe symptoms may also include loss of control over movement in part of the body, seizures and coma.
How is CVST diagnosed?
A diagnosis of CVST is usually confirmed by getting a picture of how blood is flowing in the brain. Imaging tests can reveal if blood is not draining properly. Among the tests that may be used:
- MRI scan
- CT scan
- Venography (an X-ray of the veins)
- Angiography (an X-ray of blood or lymph vessels)
- Ultrasound (a test that uses sound waves to create a picture of organs, tissues and other structures in the body)
- Blood tests
Is CVST treatable?
CVST is usually manageable if detected early. But the condition may be missed or diagnosed late because its symptoms overlap with those of other conditions. Responding quickly to warning signs or symptoms of the condition improves the likelihood of recovery.
Treatment, which should begin right away, may include fluids, antibiotics if infection is present and medicine to control seizures or stop the blood from clotting.
Since those who developed CVST after getting the J&J shot also developed low platelet counts, health officials say treatment with drugs to prevent blood clots is risky.
