Worried About Safety After Getting the Johnson & Johnson Vaccine? Here’s What to Know

EMMANUEL CROSET/AFP via Getty Images Johnson & Johnson's COVID-19 vaccine

On Tuesday morning, the Food and Drug Administration and the Centers for Disease Control recommended a temporary halt on inoculations with the Johnson & Johnson COVID-19 vaccine "out of an abundance of caution" after six people in the U.S. developed a rare blood clotting disorder within two weeks of getting the shot.

The cases were isolated and statistically low — the condition, called cerebral venous sinus thrombosis, or CVST, occurred in just six people out of the more than 6.8 million who have received the Johnson & Johnson vaccine — but the two health agencies asked for a pause to review data on the cases.

"These events appear to be extremely rare. However, COVID-19 vaccine safety is a top priority for the federal government and we take all reports of adverse events following vaccination very seriously," FDA Acting Commissioner Janet Woodcock said in a press briefing on Tuesday.

Here's what to know about CVST, and what to do if you've already received the Johnson & Johnson vaccine.

What is CVST?

CVST occurs when a blood clot forms in part of the brain, preventing blood from moving through the brain, according to Johns Hopkins Medicine. The clotted blood cells can then break and bleed into the brain tissue, causing a hemorrhage or stroke.

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The FDA and CDC recommended the pause in Johnson & Johnson vaccinations in part to help physicians look for the warning signs of CVST, especially if their patient has recently received the vaccine.

What are the symptoms?

CVST symptoms differ from the typical side effects of a COVID-19 vaccine. They can include headache, blurred vision, fainting, seizure and coma.

"For people who recently got the vaccine within the last couple of weeks, they should be aware to look for any symptoms," Dr. Anne Schuchat, the principal deputy director of the CDC, said at the briefing. "If you received the vaccine and develop severe headache, abdominal pain, leg pain, or shortness of breath, you should contact your health care provider and seek medical treatment."

For people who received the Johnson & Johnson vaccine in the last month, however, "the risk to them is very low at this time," she said.

What will the FDA and CDC do during this pause?

The two agencies said they plan to look into the six cases to determine if they were related to the vaccinations or coincidental. Dr. Peter Marks, the chief regulator of vaccines at the FDA, said that they were concerned because the "pattern is very, very similar to what was seen in Europe with [the AstraZeneca] vaccine."

"So I think we have to take the time to make sure that we understand this complication and we address it properly."

Woodcock said that they expect the pause to only last a "matter of days," and Schuchat said they are "committed to an expeditious review" in the hopes of quickly resuming Johnson & Johnson vaccinations.

Should I still get the Johnson & Johnson vaccine?

For now, most states have stopped using Johnson & Johnson vaccinations and will instead administer the vaccines from Pfizer or Moderna, which are formulated differently than Johnson & Johnson.

"We are not seeing the clotting events with low platelet counts with the other two vaccines," said Schuchat. "People who have vaccine appointments with the other two vaccines should continue with their appointments."

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The White House also said that the U.S. has enough doses of the Pfizer and Moderna vaccines to continue the vaccine rollout without interruption.

"This announcement will not have a significant impact on our vaccination plan: Johnson & Johnson vaccine makes up less than 5 percent of the recorded shots in arms in the United States to date," Jeff Zients, the White House COVID-19 Response Coordinator, said in a statement shared with PEOPLE. "Based on actions taken by the President earlier this year, the United States has secured enough Pfizer and Moderna doses for 300 million Americans."

"We are working now with our state and federal partners to get anyone scheduled for a J&J vaccine quickly rescheduled for a Pfizer or Moderna vaccine," he added.

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Once the FDA and CDC complete their review, they will say whether it is safe to continue getting the Johnson & Johnson vaccine. The health officials, however, emphasized that COVID-19 illness is still far more deadly.

"The message to the patients would be to those who haven't been vaccinated, to continue to get the vaccines that are available to them because the risks from the pandemic are significant," said Woodcock.