ORLANDO, Fla. - The U.S. on Tuesday recommended a "pause" in using the single-dose Johnson & Johnson COVID-19 vaccine to investigate reports of rare but potentially dangerous blood clots, a development that could jeopardize the rollout of vaccines around the world.
The Centers for Disease Control and Prevention and the Food and Drug Administration announced that they were investigating unusual clots that occurred 6 to 13 days after vaccination. The FDA commissioner said she expected the pause to last a matter of days.
The clots occurred in veins that drain blood from the brain and occurred together with low platelets, the fragments in blood that normally form clots. All six cases were in women between the ages of 18 and 48. One person died, and all of the cases remain under investigation.
More than 6.8 million doses of the J&J vaccine have been given in the U.S., the vast majority with no or mild side effects.
Any slowdown in the dissemination of the shots could have broad implications for the global vaccination effort. The J&J vaccine held particular promise for less affluent countries because its single-dose regimen and relatively simple storage requirements would make it easier to use in the developing world.
Federally run mass vaccination sites will pause the use of the J&J shot, and states and other providers are expected to follow. The other two authorized vaccines, from Moderna and Pfizer, make up the vast share of COVID-19 shots administered in the U.S. and are not affected by the pause.
"In these cases, a type of blood clot called cerebral venous sinus thrombosis (CVST) was seen in combination with low levels of blood platelets (thrombocytopenia)," said acting FDA Commissioner Janet Woodcock and Dr. Peter Marks, director of the Food and Drug Administration's Center for Biologics Evaluation and Research. "I’d like to stress these events appear to be extremely rare. However COVID-19 vaccine safety is a top priority."
A CDC committee will meet Wednesday to discuss the cases, and the FDA has also launched an investigation into the cause of the clots and low platelet counts.
Authorities have not seen similar clots after use of the Pfizer or Moderna vaccines, the CDC’s Dr. Anne Schuchat said.
What is cerebral venous sinus thrombosis?
According to HopkinsMedicine.org, cerebral venous sinus thrombosis (CVST) occurs when a blood clot forms in the brain’s venous sinuses. This prevents blood from draining out of the brain. As a result, blood cells may break and leak blood into the brain tissues, forming a hemorrhage.
This chain of events is part of a stroke that can occur in adults and children. It can occur even in newborns and babies in the womb. A stroke can damage the brain and central nervous system. A stroke is serious and requires immediate medical attention.
What are the symptoms of cerebral venous sinus thrombosis?
John Hopkins Medicine says symptoms include:
- Blurred vision
- Fainting or loss of consciousness
- Loss of control over movement in part of the body
What should you do if you've had the J&J vaccine?
Experts suggest if you are experiencing any of the reported symptoms within 3 weeks of having the shot, contact your health care provider.
If you have not had any side effects associated with blood clots, experts say the risk of having a reaction is unlikely.
The Associated Press contributed to this report.
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