The U.S. Food and Drug Administration (FDA) and the U.S. Centers for Disease Control and Prevention (CDC) recommended a pause in use of Johnson & Johnson (J&J)'s COVID-19 vaccine over "six reported cases of a rare & severe type of blood clot."

In a joint statement Tuesday, the CDC and the FDA said it was investigating clots in six women between the ages of 18 and 48 in the days after vaccination, in combination with reduced platelet counts. More than 6.8 million doses of the J&J vaccine have been administered in the U.S.

The J&J vaccine was the third approved vaccine in the U.S. It uses the same technology as the AstraZeneca vaccine, which was yet authorized in U.S. and linked to the possibility of causing blood clots as well.

U.S. federal distribution channels, including mass vaccination sites, will pause the use of the J&J shot, and states and other providers are expected to follow.

CDC's Advisory Committee on Immunization Practices will meet Wednesday to discuss the cases and the FDA has also launched an investigation of the cases.

"Until that process is complete, we are recommending a pause in the use of this vaccine out of an abundance of caution," 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.

(With input from agencies)