CDC, FDA Announce Pause in Use of Johnson & Johnson COVID-19 Vaccine Over Concerns of Rare Blood Clot

The FDA and CDC said that 6 women experienced cerebral venous thrombosis, an extremely rare disorder associated with blood clotting, 6 to 16 days after the Johnson & Johnson COVID-19 vaccine was administered.

The FDA and the US Centers for Disease Control and Prevention (CDC) have announced an immediate pause in the use of the Johnson & Johnson (Janssen) COVID-19 vaccine at federal sites while an investigation is conducted into 6 cases in the United States of a rare and severe type of blood clot disorder potentially linked to the vaccine.

The federal agencies announced the pause of the single-shot adenovirus Ad26.COV2.S while advising states distributing the product to consider taking similar action. In a statement, the FDA and CDC said that 6 women, aged 18-48 years, experienced cerebral venous thrombosis, an extremely rare disorder associated with blood clotting, 6 to 16 days after the vaccine was administered.

As of yesterday, more than 6.8 million doses of the vaccine have been administered in the United States and an additional 9 million doses have been shipped to various states.

“Right now, these adverse events appear to be extremely rare. COVID-19 vaccine safety is a top priority for the federal government, and we take all reports of health problems following COVID-19 vaccination very seriously,” said Anne Schuchat, MD, principal deputy director of the CDC, and Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, in a joint statement. “People who have received the J&J vaccine who develop severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after vaccination should contact their health care provider.”

FDA and CDC investigators will collaborate to determine a potential link between the vaccine and cerebral venous thrombosis and to assess whether the Emergency Use Authorization granted to the vaccine should continue or become limited. The CDC will hold an emergency meeting of the Advisory Committee on Immunization Practices on Wednesday to further review and evaluate the significance of these cases and the FDA will review that analysis as well.

“Until that process is complete, we are recommending a pause in the use of this vaccine out of an abundance of caution,” Schuchat and Marks said in the joint statement.

The FDA emphasized the importance of an indefinite pause during the investigation in a statement released on Twitter Tuesday morning.

"This is important to ensure that the health care provider community is aware of the potential for these adverse events and can plan due to the unique treatment required with this type of blood clot," they wrote.

Last month, the Biden administration announced the acquisition of an additional 100 million doses of Ad26.COV2.S to be delivered in the second half of 2021.

In early April, Janssen announced delays in manufacturing at its Baltimore plant due to the inadvertent mixing of vaccine ingredients, which resulted in the loss of up to 15 million doses.

Health care providers are asked to report any adverse events to the Vaccine Adverse Event Reporting System at