FDA and CDC recommend a "pause" in use of Johnson & Johnson's COVID vaccine

The Food & Drug Administration (FDA) and the Centers for Disease Control & Prevention (CDC) have recommended a pause in the use of Johnson & Johnson's COVID-19 vaccine "out of an abundance of caution."

In a series of tweets Tuesday morning, the FDA said it was recommending a pause after receiving reports that six people developed "rare and severe" blood clots after receiving the vaccine.

"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," the FDA said in a statement Tuesday.

So far, nearly 7 million Americans have received a dose of the Johnson & Johnson vaccine.

ABC News reports that in a statement, Johnson & Johnson wrote that safety was the company's top priority and that it met regulatory standards for reporting the adverse effects of its products.

"We are aware that thromboembolic events including those with thrombocytopenia have been reported with COVID-19 vaccines," the company said in its statement. "At present, no clear causal relationship has been established between these rare events and the Janssen COVID-19 vaccine. We continue to work closely with experts and regulators to assess the data and support the open communication of this information to healthcare professionals and the public."

The decision to pause the use of the Johnson & Johnson vaccine — currently the only single-dose vaccine approved for use in the U.S. — comes less than a week before President Joe Biden's target date to ensure all Americans are eligible for a COVID-19 vaccine.

Supplies of the Johnson & Johnson vaccine were already limited after workers at a Maryland production plant mixed up ingredients for the Johnson & Johnson vaccine and the still-to-be-approved AstraZeneca vaccine. That mix-up led to the contamination of 15 million doses of Johnson & Johnson vaccine. According to CNBC, the government only allocated 700,000 doses of J&J vaccine this week, compared to nearly 5 million last week.

There is no indication that the mix-up at the Baltimore plant is responsible for the reports of blood clotting.

This story is breaking and will be updated.