The Centers for Disease Control and Prevention will meet on Wednesday to further review the cases. The Food and Drug Administration will then review that analysis during the pause. The two agencies made the announcement to pause the shots jointly.
So what does this all mean for the millions of Americans who have already gotten the vaccine?
Who it affected and when
Six women who were given the one-shot vaccine developed a rare, severe type of blood clot. One of the women died, and one was hospitalized in critical condition.
All the women were between the ages of 18 and 48, and their symptoms occurred between six and 13 days following their vaccines.
The type of blood clot
The type of blood clot is called cerebral venous sinus thrombosis. The clots occured in veins that drain blood from the brain and occurred together with low platelets.
This particular type of blood clot, health experts emphasize, must be treated differently than other types — with different blood thinners or antibody infusions rather than the typical heparin treatment.
At a press conference with CDC and FDA officials Tuesday, it was stated that there is no indication yet of a connection between the clots and the use of birth control in women who fall between the ages of 18 and 48.
Officials said there is no indication that all of the six individuals affected had preexisting conditions that may have led to the clots.
What if I already got the shot?
Dr. Anne Schuchat, deputy director of the CDC, said for those who have gotten their vaccines a month ago or more, the risk of developing the clots is “very low at this time.”
Those who may have gotten their Johnson & Johnson shots in the last couple of weeks should monitor their symptoms.
The clots have usually occurred about a week after the shots and not longer than three weeks with a median of about nine days after vaccination.
What are the symptoms?
Schuchat said the clotting symptoms are different from the mild, flu-like symptoms many experience in the couple of days following their vaccine.
Those who experience severe headaches, abdominal pain, leg pain or shortness of breath within three weeks after getting their shot should contact their health care provider.
Should I still get a COVID-19 vaccination?
Health officials emphasized that they “are not seeing these clotting events…with the other two vaccines,” Moderna and Pfizer.
Schuchat said people who already have appointments to receive the Pfizer and Moderna vaccines should keep their appointments.
As far as the Johnson & Johnson vaccine, several states are recommending the pause as well. Some vaccination clinics have already announced they will pause the distribution of the vaccines.
Health officials will work with individuals who have scheduled Johnson & Johnson vaccines in the days ahead to make sure they get their vaccinations when they are available, said Schuchat.
Will the U.S. resume Johnson & Johnson vaccines?
Dr. Janet Woodcock, acting FDA commissioner, said the recommended pause on the vaccine will likely last just a matter of days.
The pause is meant “to prepare the health care system” to properly treat patients that may develop the clots and to report the severe events they may see in recipients, said Schuchat.
The agencies will also revise their fact sheets on the Johnson & Johnson vaccine for recipients and health care providers.
“When we saw this pattern and were aware that treatment needed to be individualized for this condition, it was of the utmost importance to us to get the word out. The pandemic is quite severe…vaccinations are critical, so we want to make sure we make some recommendations quickly,” said Schuchat.
The Associated Press contributed to this story.