The U.S. Food and Drug Administration (FDA) said one person had died from the rare blood clotting condition after taking the J&J vaccine and another was in a critical condition.
FDA acting commissioner Janet Woodcock said her agency expected the pause to be a matter of days, and it was aimed at providing information to healthcare providers so that they can diagnose, treat and report such blood clots.
FDA official Peter Marks said that part of the reason for the pause was to warn doctors that administering the standard treatments for clots can cause tremendous harm, or be fatal.
"The issue here with these types of blood clots is that if one administers the standard treatment that we as doctors have learned to give for blood clots, one can actually cause tremendous harm," said Marks.
The Centers for Disease Control and Prevention's deputy director Anne Schuchat said if patients received the J&J vaccine and developed "severe headache, abdominal pain, leg pain or shortness of breath," then they should seek medical treatment.
The health officials said there had been no similar blood clot cases reported among recipients of the Pfizer/BioNTech or Moderna vaccines.