The Centers for Disease Control and Prevention (CDC) is investigating two new cases of a rare, severe blood clot that occurred alongside low platelets in Johnson & Johnson COVID-19 vaccine recipients, bringing the total number of instances to 17. A CDC spokesperson told Fox News that one case of thrombosis with thrombocytopenia syndrome (TTS) under investigation occurred in a male vaccine recipient, and the other in a female, both under age 60.

It was not clear if the male patient was the same individual in California who is receiving treatment at the University of California San Francisco medical center.

"Investigations are ongoing," a CDC spokesperson told Fox News via email. "To protect patient privacy CDC does not provide information about cases of adverse events after vaccines that might potentially identify the patients."

CALIFORNIA MAN WHO RECEIVED JOHNSON & JOHNSON COVID-19 VACCINE HOSPITALIZED WITH BLOOD CLOT

The spokesperson said the agency along with the FDA is continuing to monitor for reports of TTS through the Vaccine Adverse Event Reporting System (VAERS).

FDA LIFTS JOHNSON & JOHNSON COVID-19 VACCINE PAUSE FOLLOWING SAFETY REVIEW

The CDC along with the FDA had acted to lift a temporary pause that was placed on the national rollout after determining that the benefits of the vaccine outweigh the risks. About 8.1 million doses of the Johnson & Johnson vaccine had been administered in the U.S.

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"There is no greater priority than the safety and well-being of the people we serve, and we carefully review reports of adverse events in individuals receiving our medicines or vaccines. Any report about an individual receiving our COVID-19 vaccine and our assessment of that report is shared with the U.S. Food and Drug Administration and other appropriate health authorities," a spokesperson for Johnson & Johnson told Fox News in a statement. "This is part of the established process to inform health authorities’ comprehensive surveillance programs that monitor the overall safety of medicines, as well the vaccines authorized for use against this pandemic."