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CDC narrows use of J&J vaccine due to concerns about rare blood clots

Doses of the Johnson & Johnson COVID vaccine is packaged in a box at the McKesson facility on March 1, 2021 in Shepherdsville, Kentucky.
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Doses of the Johnson & Johnson COVID vaccine is packaged in a box at the McKesson facility on March 1, 2021 in Shepherdsville, Kentucky.

Updated December 16, 2021 at 8:07 PM ET

The Centers for Disease Control and Prevention accepted advice from a panel of experts to recommend the use of the Moderna and Pfizer-BioNTech COVID-19 vaccines over the Johnson & Johnson jab, following growing concerns about rare blood clots.

The advisers said Thursday that vaccines from Pfizer and Moderna should be preferred by all adults, who may be at greater risk for developing severe blood clots from the J&J vaccine than those under age 18. Some committee members said the J&J vaccine should remain available for people who prefer it.

The recommendation was prompted by the occurrence of a rare and sometimes fatal blood-clotting problem called thrombosis with thrombocytopenia syndrome (TTS). Earlier reports of the issue addressed cases of cerebral venous sinus thrombosis (CVST), a type of TTS.

In a statement, Johnson & Johnson said it "remains confident in the overall positive benefit-risk profile" of its vaccine.

"The safety and well-being of those who use the Johnson & Johnson vaccine continues to be our number one priority," said Dr. Mathai Mammen, head of drug research and development at Johnson & Johnson, in the statement. "We appreciate today's discussion and look forward to working with the CDC on next steps."

The blood clots are extremely rare, the CDC says

The CDC said the problem is rare, but it has been seen at a rate of about one case in every 100,000 doses given to women 30 to 49 years old — the group at highest risk. About 15% of cases of TTS have been fatal, according to CDC data.

The symptoms of TTS vary, but they can include headache, blurred vision, fainting or loss of consciousness, loss of control over movement in part of the body and seizures.

In April, the CDC and the Food and Drug Administration recommended a temporary pausein use of the vaccine after six cases of the rare blood clots were seen in the United States. Later that month, the agencies rescinded the pause after an analysis of available data showed that the benefits of the vaccine outweigh its risks. Since then, more data has been gathered confirming the initial reports of blood clots.

A key advantage of the J&J jab was already eroded

The J&J vaccine was authorized by the FDA as a one-dose vaccine, compared with the two doses for the vaccines from Moderna and Pfizer. But the advantage of a one-dose vaccine for some people has been eroded by a CDC recommendation in September that people who got the J&J vaccine receive a booster two months later.

More than 16 million people in the U.S. have been immunized with a shot of the J&J vaccine. More than 870,000 have received a J&J booster.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

Vanessa Romo is a reporter for NPR's News Desk. She covers breaking news on a wide range of topics, weighing in daily on everything from immigration and the treatment of migrant children, to a war-crimes trial where a witness claimed he was the actual killer, to an alleged sex cult. She has also covered the occasional cat-clinging-to-the-hood-of-a-car story.
Scott Hensley edits stories about health, biomedical research and pharmaceuticals for NPR's Science desk. During the COVID-19 pandemic, he has led the desk's reporting on the development of vaccines against the coronavirus.