WASHINGTON (NewsNation Now) — The Centers for Disease Control and Prevention Advisory Committee on Immunization Practices will meet Wednesday to discuss the rare but potentially dangerous blood clot cases that led the agency to recommend pausing the use of Johnson & Johnson’s single-dose COVID-19 vaccine.

The virtual emergency meeting is scheduled to begin at 1:30 p.m. ET. NewsNation will effort live coverage of the meeting online and the NewsNation Now app.

The Food and Drug Administration and CDC Tuesday recommended pausing the use of the vaccine for at least a few days to investigate after six cases of blood clots were reported.

More than 6.8 million doses of J&J have been administered, according to the FDA.

“I’d like to stress these events appear to be extremely rare. However COVID-19 vaccine safety is a top priority,” FDA Acting Commissioner Janet Woodcock said at a news conference Tuesday. “We expect it to be a matter of days for this pause.”

The agencies are recommending that people who were given the J&J vaccine who are experiencing severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after receiving the shot contact their health care provider.

Dr. Anthony Fauci, the nation’s top infectious diseases expert, echoed the agencies Tuesday saying the chances of the blood clots occurring are less than one in a million but Americans should pay attention if they received the vaccine.

“It’s less than one in a million.” Fauci adds people should “pay attention” to symptoms associated with the blood clots, particularly between one and three weeks after the shot.

“Don’t get an anxiety reaction,” Fauci said Tuesday.

Jeff Zients, the White House COVID-19 response coordinator, said the J&J pause will not have a “significant impact” on the country’s vaccination plan, adding that J&J vaccines make up less than 5 percent of the recorded shots in arms in the U.S. to date.

On Wednesday, the White House COVID-19 Response Team and federal public health officials will hold a press briefing to provide updates on the COVID-19 response effort.

The FDA said the cases under investigation appear similar to unusual clots that European authorities say are possibly linked to another COVID-19 vaccine not yet cleared in the U.S., from AstraZeneca. European regulators have stressed that the AstraZeneca risk appears to be lower than the possibility of developing clots from birth control pills.

J&J said in a statement it was aware of the reports of blood clots, but that no link to its vaccine had been established. The company also said it is delaying the rollout of its vaccine in Europe as a precaution.

The Associated Press, Nexstar Media Wire and Reuters contributed to this report.