The blood clot called cerebral venous sinus thrombosis was seen in combination with low levels of blood platelets in these cases, the federal agencies said.
Moderna and Pfizer make up the vast majority of doses on hand in the State of Illinois, state officials said in a statement Tuesday.
As the manufacturer has run into supply problems, however, Pritzker has downplayed its importance at the current stage of the vaccination effort.
The officials said they are reaching out to state and local health officials, pharmacies and physicians who have been giving the vaccines to make sure they know about the pause, and know how to evaluate people for symptoms. They encourage people to keep appointments of the Pfizer and Moderna vaccines, and the agencies’ partners will work with people to reschedule appointments for the Johnson & Johnson vaccine.