WASHINGTON — The United States on Tuesday recommended pausing the use of the Johnson & Johnson COVID-19 vaccine to investigate reports of a handful of cases involving very rare, but potentially dangerous, blood clots.
The Centers for Disease Control and Prevention and the Food and Drug Administration said they are looking into six cases of the clots that occurred in women, ages 18 to 48, several days after they received the single-dose vaccination.
Below is everything you need to know about the pause, the shots and what to be aware of if you already received the Johnson & Johnson vaccine.
Why is the Johnson & Johnson COVID vaccine paused?
The U.S. is recommending a “pause” of the administration of the single-dose Johnson & Johnson COVID-19 vaccine to investigate "extremely rare" reports of a specific kind of blood clot.
Federal health officials said they expect the pause will last only "a matter of days" and will give time to inform the healthcare system about how to recognize and treat patients appropriately.
In a joint statement Tuesday, the Centers for Disease Control and Prevention and the Food and Drug Administration said they were investigating unusual clots in six women that occurred 6 to 13 days after vaccination.
The clots occurred in veins that drain blood from the brain and occurred together with low platelets. All six cases were in women between the ages of 18 and 48.
More than 6.8 million doses of the J&J vaccine have been administered in the U.S., the vast majority with no or mild side effects.
U.S. health authorities noted that when these clots occur with low platelet count, as seen in these six cases, a typical clot treatment could do more harm. Officials said this pause will give time to let healthcare providers know what they should be on the lookout for.
What if you already got the Johnson & Johnson vaccine? What are the symptoms to look for?
Dr. Anne Schuchat, CDC Principal Deputy Director, said people who recently got the vaccine should be aware to look for any symptoms and added that the risk is very low at this time for those who got it more than a month ago.
"For people who got the vaccine more than a month ago, the risk to them is very low at this time. For people who recently got the vaccine within the last couple weeks, they should be aware to look for any symptoms," Dr. Schuchat said. "If you've 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. Now these symptoms are different from the mild flu-like symptoms, fever and so forth, that many people experience in the couple days after receipt of the vaccine."
Dr. Peter Marks, director of FDA Center for Biologics Evaluation and Research, noted that these cases have usually occurred about a week after vaccination and no later than 3 weeks after vaccination.
How are these symptoms different from typical COVID vaccine side effects?
Mild flu-like symptoms typically occur within a couple of days of receiving a COVID-19 vaccine and go away in a few days. According to the CDC, the common side effects specifically from the vaccine include pain, redness, and swelling in the arm where you received the shot, as well as tiredness, headache, muscle pain, chills, fever, and nausea throughout the rest of the body.
What officials say you should watch out for related to these blood clots is severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after receiving the Johnson & Johnson shot.
Cerebral venous sinus thrombosis
The CDC and FDA said in a statement that in the known six cases, "a type of blood clot called cerebral venous sinus thrombosis (CVST) was seen in combination with low levels of blood platelets (thrombocytopenia)."
According to Johns Hopkins Medicine, CVST affects about 5 people in 1 million each year.
Does this impact Pfizer or Moderna vaccinations?
No. Moderna and Pfizer, which make up the vast share of COVID-19 shots administered in the U.S., are not affected by the J&J pause and there have been no reports of this possible issue related to those 2-dose vaccines.
Federal health officials stressed Tuesday that if you have an appointment to receive a Moderna or Pfizer COVID-19 vaccine, you should go ahead and get the shots.
Is this the same as the AstraZeneca vaccine?
So far, the reports appear similar to a rare, unusual type of clotting disorder that European authorities say is possibly linked to the AstraZeneca COVID-19 vaccine.
The Johnson & Johnson and AstraZeneca vaccines are made with the same technology. Leading COVID-19 vaccines train the body to recognize the spike protein that coats the outer surface of the coronavirus. But the J&J and AstraZeneca vaccines use a cold virus, called an adenovirus, to carry the spike gene into the body.
However, the J&J vaccine uses a human adenovirus to create its vaccine while AstraZeneca uses a chimpanzee version.
The European Medicines Agency stressed that the benefits of receiving the AstraZeneca vaccine outweigh the risks for most people. But several countries have imposed limits on who can receive the vaccine; Britain recommended that people under 30 be offered alternatives.
How many cases of blood clots in the US?
Of the more than 6.8 million Americans who have received a Johnson & Johnson COVID-19 vaccine, there have been six cases of these rare blood clots and low platelet counts.
The cases involved six women, between the ages of 18 and 48. Health officials said they reported the clots 6 to 13 days after receiving the vaccine.
According to CDC data, about 9 million Johnson & Johnson coronavirus vaccines have been delivered to states and are waiting to be administered.
Again, of the 6.8 million doses of the J&J vaccine that have been administered in the U.S., the vast majority had no or mild side effects.
Where is the vaccine paused?
U.S. federal distribution channels, including mass vaccination sites, will pause the use of the J&J shot, and states and other providers are expected to follow.
Will J&J pause eventually be lifted?
The FDA says it expects a short pause of Johnson & Johnson vaccines while regulators investigate reports of potentially dangerous clots in a small number of patients.
Dr. Janet Woodcock, the agency’s acting commissioner, says, “We expect it to be a matter of days for this pause.”
The CDC's Advisory Committee on Immunization Practices will meet Wednesday to discuss the cases and the FDA has also launched an investigation into the cause of the clots and low platelet counts.
Johnson & Johnson said it was aware of the reports of “thromboembolic events,” or blood clots, but that no link to its vaccine had been established.