The FDA and CDC are recommending that the U.S. pause the use of the Johnson & Johnson COVID-19 vaccine after reports of blood clots in some individuals who have received that vaccine.

On Tuesday morning the health agencies released a statement saying “out of an abundance of caution,” they are making this recommendation saying blood clots still seem to be “extremely rare.” At this point, the CDC and FDA are looking at six reported cases in the U.S. where they are reporting that this has taken place.

All six recipients were women between the ages of 18 and 48, with symptoms occurring 6 to 13 days after vaccination, according to the statement. One woman died and one has been hospitalized in critical condition.

Johnson & Johnson released a statement Tuesday saying it also was reviewing the cases with European health authorities and has decided to delay the rollout of its vaccine in Europe.

“The safety and well-being of the people who use our products is our No. 1 priority,” read the company statement. “We have been working closely with medical experts and health authorities, and we strongly support the open communication of this information to healthcare professionals and the public.”

The CDC’s Advisory Committee on Immunization Practices (ACIP) will hold a meeting Wednesday to review the blood clotting cases. The FDA said it will also investigate the cases and review the committee’s analysis.

“Until that process is complete, we are recommending this pause,” Dr. Anne Schuchat, Principal Deputy Director of the CDC and Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research said in a joint statement. 

According to the CDC. as of Tuesday, there have been more than 6.8 million doses of the Johnson & Johnson vaccine administered in the U.S. and approximately 9 million more has been shipped out to states,