FDA, CDC recommend pausing use of Johnson & Johnson vaccine after reports of rare but severe blood clots

The Food and Drug Administration and the Centers for Disease Control and Prevention recommended a pause in administering the Johnson & Johnson COVID-19 vaccine after reports of blood clots in a small number of people who received it.

The health agencies released a statement Tuesday morning recommending the pause “out of an abundance of caution,” saying blood clots seem to be “extremely rare.” The CDC and FDA are reviewing six reported cases out of nearly 7 million Johnson & Johnson vaccines administered in the USA.

All six were in women ages 18 to 48, and symptoms occurred six to 13 days after vaccination, according to the agencies. One woman died, and one was hospitalized in critical condition.

Johnson & Johnson released a statement Tuesday saying it was reviewing the cases with European health authorities and decided to delay the rollout of its vaccine in Europe.

"The safety and well-being of the people who use our products is our No. 1 priority," the company statement said. "We have been working closely with medical experts and health authorities, and we strongly support the open communication of this information to healthcare professionals and the public."

The CDC’s Advisory Committee on Immunization Practices (ACIP) will hold a meeting Wednesday to analyze the cases. The FDA said it will review the committee’s analysis as it investigates.

“Until that process is complete, we are recommending this pause,” Dr. Anne Schuchat, principal deputy director of the CDC, and Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said in a joint statement. “This is important to ensure that the health care provider community is aware of the potential for these adverse events and can plan due to the unique treatment required with this type of blood clot.”

Health officials said during a joint briefing Tuesday the pause is expected to last "a matter of days" but noted the duration would be determined by how quickly they can review the available information and contact clinicians to ensure proper diagnosis and treatment.

“I know there are people who have gotten the vaccine who are probably very concerned,” Schuchat said during the briefing.

What you should know: The FDA and CDC recommend pausing the use of Johnson & Johnson's COVID-19 vaccine

Anyone who received the vaccine more than a month ago is at very low risk, she said.

Those who got it within the past three weeks should monitor for symptoms such as severe headache, abdominal pain, leg pain or shortness of breath, and if symptoms develop, people should seek medical care.

“These symptoms are different from the mild, flu-like symptoms, fever and so forth that many people have experienced in the couple of days after receipt of the vaccine,” Schuchat said.

People who received the J&J vaccine more than three weeks ago probably are in the clear, said Dr. Geoffrey Barnes, a vascular medicine specialist at the University of Michigan, but he urged "self-awareness with your own health."

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“Remain calm,” he said. “People should overall feel reassured that they got the vaccine and should have protection developing from COVID.”

The FDA detected the extremely rare side effect because it differed from typical, though also rare, blood clotting events. The type of blood clot reported in individuals who received the J&J vaccine is called cerebral venous sinus thrombosis (CVST).

CVST occurs in two to 14 people per million and is familiar to doctors. In those cases, the patient’s blood platelet count is normal.

In the Johnson & Johnson cases, patients had this condition in combination with extremely low platelet counts, known as thrombocytopenia, Marks said.

“And that pattern is very, very similar to what was seen in Europe with other vaccines,” he said, referring to the AstraZeneca COVID-19 vaccine.

In most clinical settings, an anticoagulant drug called heparin is administered to treat blood clots; however, health officials said using this drug in these instances could be dangerous, and they recommended alternative treatments.

Health officials don’t know the definitive cause of the blood clots but suspect similarities in cases of blood clots in a small number of people who received the AstraZeneca vaccine, which is made using the same technique as the Johnson & Johnson vaccine.

The immune system of the person who got the vaccine may react to the vaccine by attacking the body's own blood platelets or other parts of the coagulation system.

“That’s the leading theory or hypothesis about what’s going on,” acting FDA Commissioner Janet Woodcock said.

As of Monday, more than 6.8 million doses of the Johnson & Johnson vaccine had been administered in the USA, and approximately 9 million more had been shipped out to states, according to the CDC.

“COVID-19 vaccine safety is a top priority for the federal government, and we take all reports of health problems following COVID-19 vaccination very seriously,” Schuchat and Marks said.

When asked whether pausing was an overreaction since adverse incidents are "extremely rare," Schuchat said "it was of the utmost importance (to) get the word out" as officials learned treatment needed to be individualized.

"The pandemic is severe and cases are increasing and vaccinations are critical," she said. "So we wanted to make recommendations quickly."

States and pharmacies moved quickly to pause vaccinations with the J&J vaccine after the FDA and CDC recommendation. Some sites canceled scheduled appointments or offered available doses of the Moderna or Pfizer-BioNTech vaccine instead.

The pause could complicate the country’s vaccination rollout plans, especially after the Biden administration moved up the deadline to make all adults eligible for a COVID-19 vaccine from May 1 to April 19.

The J&J vaccine received emergency use authorization from the FDA in late February. The company promised 100 million single-shot doses to the U.S. government by the end of May.

The one-shot vaccine played an important role in the country’s strategy to combat COVID-19 as it meant more people could become protected sooner as vaccine eligibility opened to millions of younger people, said Peter Pitts, president and co-founder of the Center for Medicine in the Public Interest. The pause could slow down these efforts but not totally disrupt them.

“Clearly the J&J vaccine is an incredibly important tool,” he said. “The J&J vaccine was not the product being used by the majority of states, so it’s not going to be as much of a problem as if it were Moderna or Pfizer.”

However, the U.S. government will need to prepare in case health officials decide to remove the J&J vaccine from the market, he added.

The J&J vaccine makes up less than 5% of U.S. vaccinations, according to a statement from Jeff Zients, White House COVID-19 response coordinator. The federal government has shipped more than 25 million doses of the Pfizer-BioNTech and Moderna vaccines each week and is on track to make available 28 million doses this week.

"This is more than enough supply to continue the current pace of vaccinations of 3 million shots per day, and meet the President's goal of 200 million shots by his 100th days in office – and continue on to reach every adult who wants to be vaccinated," Zients said.

Health experts emphasized there have been no reports of such problems with the Pfizer-BioNTech and Moderna vaccines, which utilize a different technology from the AstraZeneca and J&J vaccines, and Americans should follow through with those vaccinations.

Follow Adrianna Rodriguez: @AdriannaUSAT.

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This article originally appeared on USA TODAY: J&J vaccine paused: CDC, FDA cite blood clots in COVID vaccine