U.S. pauses Johnson & Johnson vaccine due to concerns over blood clots

More than 6.8 million doses of the Johnson & Johnson (Janssen) vaccine have already been administered in the U.S. However, on Tuesday, the CDC and FDA recommended a pause in the one-dose vaccine due to blood clot concerns.

The CDC and FDA are reviewing data involving six reported U.S. cases of a rare and severe type of blood clot in individuals after receiving the J&J vaccine. All six cases occurred among women between the ages of 18 and 48, and the symptoms occurred six to 13 days after vaccination.

Treatment of this specific type of blood clot is different from the treatment that might typically be administered, according to the CDC. Usually, an anticoagulant drug called heparin is used to treat blood clots. In this setting, administration of heparin may be dangerous, and alternative treatments need to be given.

CDC will convene a meeting of the Advisory Committee on Immunization Practices (ACIP) on Wednesday to further review these cases and assess their potential significance. FDA will review that analysis as it also investigates these cases.

Until that process is complete, the agencies are recommending a pause in the use of this vaccine out of an abundance of caution. This is important, in part, to ensure that the health care provider community is aware of the potential for these adverse events and can plan for proper recognition and management due to the unique treatment required with this type of blood clot.

Right now, these adverse events appear to be extremely rare, the CDC noted. People who have received the J&J vaccine who develop a severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after vaccination should contact their health care provider.

CDC and FDA provided additional information and answered questions at a media briefing on Tuesday. Find a recording of that media call here.