WASHINGTON (WGHP/NewsNation) — The Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) on Tuesday recommended pausing the use of Johnson & Johnson’s single-dose COVID-19 vaccine after six cases of blood clots were reported.

In a joint statement, the FDA and CDC said it was investigating clots in six women in the days after vaccination, in combination with reduced platelet counts. The agencies say the adverse events appear to be extremely rare.

U.S. government-run vaccine sites are expected to stop offering the Johnson & Johnson coronavirus vaccine, according to the New York Times. The Times reported that one woman died from a possibly vaccine-related clot. Another is in critical condition.

All six of the patients were women between ages 18 and 48.

According to the FDA, more than 6.8 million doses of J&J have been administered. 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. The government is only recommending that states halt usage of the vaccine but is not requiring them to stop.

CDC’s Advisory Committee on Immunization Practices will meet Wednesday to discuss the cases and the investigation into 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.