The Johnson & Johnson COVID-19 Vaccine Blood Clot

New Delhi, Agency News: The recommendation to pause the use of the Johnson & Johnson COVID-19 vaccine continues after an advisory committee of independent experts to the U.S. Centers for Disease Control and Prevention (CDC) said it needed more information to understand the possible connection to an extremely rare but serious blood clotting disorder.

What Autoimmune and Inflammatory Disease Patients Need to Know

Many in the CreakyJoints and Global Healthy Living Foundation community, who have underlying health conditions — including some that can increase the risk of blood clots — naturally have many questions about what this news means for them. Chief among them: What if I already received the J&J vaccine — should I be worried? When the pause is lifted, is this vaccine still safe to get?

People with certain chronic diseases may have special concerns about the Johnson & Johnson vaccine, given their medical history and risk factors for blood clots.

This is a developing story and the experts we spoke with emphasized that much more is still unknown than know. The main takeaways right now:

  • Experts still do not know whether the vaccine is related to or caused this blood clotting issue.
  • The pause is recommended out of an abundance of caution so scientists can review data and decide if vaccine recommendations may need to change.
  • This “pause” process should help build confidence in our vaccine safety system. By being able to flag a very rare possible side effect as early in the vaccine rollout as possible, it shows that experts are taking safety seriously.
  • The specific blood clotting disorder being studied is exceedingly rare and not the same as other types of blood clots that are much more common.
  • Because this blood clotting disorder is so rare, it’s not known that having other conditions or risk factors makes you more likely to get it.
  • If you are scheduled to get a different COVID-19 vaccine during the pause, you should still get it. No cases of this blood clotting issue have been reported among the more than 180 million people who received the Pfizer-BioNTech or Moderna vaccines, according to the CDC.

As we continue to learn more, the important message to remember is this: “Please continue to get vaccinated with other COVID-19 vaccines,” says Vinicius Domingues, MD, a rheumatologist in Daytona Beach, Florida, and medical advisor to CreakyJoints.

Why the Johnson & Johnson COVID-19 Was Paused

Experts were already aware of a similar issue with blood clots linked to the AstraZeneca COVID-19 vaccine because of reports in Europe that led to pauses and restrictions in the use of the vaccine there. The Johnson & Johnson vaccine is made similarly to the AstraZeneca vaccine.

Then they observed a “safety signal” in the U.S. reporting system for adverse events following vaccination: six cases of very rare and severe blood clots in the brain that affected women after they received the Johnson & Johnson vaccine. All women were between the ages of 18 and 48; one person died. Some people also had blood clots in other parts of their bodies, including their lungs and limbs. As the CDC advisory panel reviewed more data, they discovered a couple of additional cases, including a seventh woman and a man who developed the rare condition during the vaccine clinical trial.

This means there have been eight cases documented out of more than 7 million people who received the vaccine.

Although blood clots are generally common — affecting 900,000 Americans a year, according to the CDC — this particular type of blood clotting issue is very, very rare.

It is called cerebral venous sinus thrombosis (CVST) — blood clots in the brain — with thrombocytopenia (low platelet levels in the blood). This is a highly unusual combination of symptoms because normally platelets cause the blood to clot. You wouldn’t expect to see low levels of platelets along with blood clotting.

The CDC and the U.S. Food and Drug Administration (FDA) issued the pause earlier this week in order to give experts time to review additional data to determine whether this very rare disorder 1) is directly related to the vaccine, and 2) if there should be a change in recommendations as to who should receive the Johnson & Johnson vaccine.

What Experts Know and Don’t Know

To be clear, the CDC says that we still do not know enough yet to say if the vaccine is related to or caused this health issue.

But there are clear signals of concern, in part because this particular combination of blood clotting with low platelets is exceedingly rare.

A key question is understanding the “background rate” for this condition, or the number of events that would be expected to occur naturally in people who didn’t get the vaccine. That number itself, however, is hard to determine because, as experts are stressing, CVST with thrombocytopenia is so uncommon. CDC safety expert Tom Shimabukuro, MD, estimated that the clotting disorder in women ages 20 to 50 who received the Johnson & Johnson vaccine occurred at least three times more often than would be expected.

Keep in mind, however, that if it were just the vaccine causing this problem, many, many more people would have it. “Some quirk of biology very likely predisposes certain people to have a bad reaction to the vaccine.” If the vaccine alone were responsible, there would be many more cases.

There is still a lot that experts do not know about this condition, including:

Risk Factors

For example, there don’t seem to be any obvious common risk factors among those affected. No patients were pregnant or postpartum, and only one was using oral contraceptives. (Being pregnant or postpartum and taking birth control can raise your risk of blood clots.) No one had any pre-existing blood clotting disorders.

Occurrence in Men and Older Adults

We also don’t know whether the condition may affect older people or men more than is currently thought.

Rates Among Those with COVID

We know blood clotting commonly affects people infected with COVID-19 and plays a big role in complications, hospitalization, and organ damage. It’s also important to understand whether this rare disorder also affects people who have COVID-19 because that could affect how we perceive the risks and benefits of the vaccine in relation to COVID.

How Could the Vaccine Cause This Blood Clotting Disorder?

Both the AstraZeneca and Johnson & Johnson COVID-19 vaccines use adenoviruses to carry DNA instructions into our cells that teach our immune system how to recognize the coronavirus in order to make antibodies against it.

Because there is no connection between this rare blood clotting disorder and the vaccines from Pfizer and Moderna, which use different technology, researchers suspect that there could be something about the adenovirus that is playing a role in this rare disorder.

Researchers examined data from a small group of European patients who developed rare blood clots after they received the AstraZeneca vaccine. They found that the patients had developed rare antibodies — an immune system response — to proteins involved in blood clot formation.

“However, it’s not yet clear whether people who develop reactions to the vaccines already have some platelet factor 4 antibodies before they are vaccinated, or whether the vaccines somehow spur the body to make these antibodies, which then launch a kind of autoimmune attack.”

This is just one possible explanation.

If a causal link between the Johnson & Johnson vaccine (and AstraZeneca vaccine) and CVST with thrombocytopenia is established, more research will be needed to understand what is driving it.

What to Look for If You’ve Had the J&J Vaccine Recently

All of the people who experienced this blood-clotting disorder developed symptoms within about two weeks of receiving the vaccine. The CDC says that if you got the vaccine more than three weeks ago, your risk of developing a blood clot is very low.

If you got the vaccine within the last three weeks, remember that your risk of developing this kind of blood clot is also very low. But it’s wise to be on the lookout for the following symptoms of a blood clot:

  • Severe headache
  • Blurred vision
  • Fainting
  • Seizures
  • Pain in your abdomen (chest or stomach)
  • Leg pain or swelling
  • Shortness of breath

If you experience any of these, seek medical attention and tell your provider that you recently received the Johnson & Johnson vaccine.

The overwhelming odds are that you do not have cerebral venous sinus thrombosis with thrombocytopenia.

But it’s important for your provider to know because the blood thinner medication heparin, which is a common treatment for clots, can harm people with this particular type of blood clotting and should not be used.

What to Know If You Have Risk Factors for or a History of Blood Clots

This is an area where experts are hesitant to make any definite recommendations because so little is known about this rare blood clotting disorder. Just because you may be at increased risk for other kinds of clots DOES NOT MEAN you are at increased risk for CVST with thrombocytopenia.

Many health conditions and medications can increase your risk for more common kinds of blood clots, known as deep vein thrombosis (DVT). They can be more common in some autoimmune and rheumatic conditions, including rheumatoid arthritis, lupus, and inflammatory bowel disease.