COVID-19 vaccine blood clots: Should you be concerned?

The Johnson & Johnson COVID vaccine was paused over concerns of blood clots. Here's the real amount of risk.

Sean Jackson
Sean Jackson is a creative copywriter living in Florida. He's had work published with Realtor.com, theScore, ESPN, and the San Francisco Chronicle. In his free time, Sean likes to play drums, fail miserably at improv and spend time at the beach.
Sean Jackson
6 min read

Blood clots can be serious, but the risk of getting one from a COVID-19 vaccine remains low.

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By now, you've likely heard about the concerns of developing blood clots after receiving the Johnson & Johnson COVID-19 vaccine. If not, allow us to get you up to speed.

On April 13, the Food and Drug Administration and the Centers for Disease Control and Prevention released a joint statement recommending a brief pause in administering the Johnson & Johnson/Janssen COVID-19 vaccine to patients, while the agencies investigate six confirmed reports of patients -- all women -- who experienced severe blood clots (specifically, cerebral venous sinus thrombosis) after receiving the dose. On April 23, both agencies lifted the pause recommendation after finding that the severe blood clotting cases were "very rare events." 

This isn't the first COVID-19 vaccine that has raised concerns about blood clots. The European Union announced that the AstraZeneca COVID-19 vaccine produced rare instances of blood clots in women under the age of 60 with low blood platelets. Some European countries paused using the vaccine in March after two vaccinated patients died. However, the European Medicine Agency suggests blood clots are a rare side effect and the benefit of the vaccine outweighs the risks. 

So, what exactly is your risk of developing a blood clot from the vaccine, and should you be concerned? Considering that around over 7.2 million people have received the Johnson & Johnson/Janssen vaccine and six people have experienced blood clots, the risk is extremely low. Still, it's a health concern you should be aware of.

In general, blood clots can lead to dangerous health events like a strokeheart attack or pulmonary embolism. This guide will help you better understand what blood clots are, the risk levels of suffering a blood clot after your shot and symptoms to watch for after your vaccine that could indicate you might have a clot.


The Johnson & Johnson vaccine may have caused blood clots in six patients out of 7.2 million people who have received the vaccine.

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What are blood clots?

The Cleveland Clinic explains that blood clots form when your blood collects into a gellike substance in your veins or arteries, typically after some kind of injury. They are made from platelets and fibrin, two types of blood cells that combine to create a platelet plug, which stops the cut or tear from bleeding. These are typically harmless and are a key part of the healing process.

However, if they do not dissolve on their own, or the clots form in dangerous areas (in blood vessels near the heart, brain or lungs), it can lead to a health emergency called thrombosis. When a blood clot breaks away from your blood vessel and moves to a new part of your body, it's called an embolism. This creates a serious medical risk because those blood clots could end up in your heart, brain or lungs, and cause a catastrophic event like a stroke, heart attack or pulmonary embolism. As many as 100,000 people may die annually from blood-clot-related illnesses, according to the Cleveland Clinic

There are common triggers that produce blood clots, including family history, cancer and smoking cigarettes. If you are pregnant or taking birth control pills, you might also be at a slightly elevated risk of having blood clots.

Another common cause is COVID-19. The Center for Disease Research and Policy at the University of Minnesota found those who had COVID-19 had a 100 times greater risk of having blood clots than the general population. This is why medical professionals are still urging everyone to get the COVID-19 vaccine, because the risk of getting blood clots from COVID-19 is significantly higher than getting them from the vaccine.

The few who developed blood clots after taking the Johnson & Johnson/Janssen COVID-19 vaccine developed CVST, a specific type of blood clot that develops in the brain.

Johns Hopkins Medicine explains that CVST is dangerous because it prohibits the brain from draining blood, which could result in a hemorrhage. For CVST, there are a variety of treatment methods. They include prescribing anticoagulants to prevent clotting, fluids, antibiotics, controlling pressure inside of the head and surgery in some cases.


Blood clots can block blood flow, causing heart attacks, strokes and pulmonary embolisms.

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What is the level of risk for blood clots with the COVID vaccines?

Of the over 6.8 million who received the Johnson & Johnson/Janssen vaccine, only six reported significant problems with blood clotting. ABC News reports that of those six, one passed away, two are in the ICU, two are in the hospital and one has been discharged. On April 23, the Advisory Committee on Immunization Practices reported the number of cases reported had grown to 15 -- three women died. 

There are commonalities between those who suffered blood clots after taking the Johnson & Johnson and the AstraZeneca vaccines. The European Medicines Agency says that most of the AstraZeneca cases reported were in women under the age of 60, while ABC News states all six blood clot patients from the Johnson & Johnson vaccine group were Caucasian females with a median age of 33. None of the patients had coagulation disorders, though three were obese, one had asthma and one patient had high blood pressure. 

Although there are no restrictions on who can receive the Johnson & Johnson vaccine, the CDC acknowledges the risk of a severe blood clotting event is much higher -- but still rare -- in women under 50. On its website, the CDC states that "women younger than 50 years old especially should be aware of the rare but increased risk of this adverse event, and that there are other COVID-19 vaccine options available for which this risk has not been seen." In the US, Pfizer and Moderna vaccines are widely available and carry no increased risk of blood clots. 

Overall, the apparent risks of incurring blood clots from a COVID-19 vaccine are lower than taking birth control. The University of Minnesota states that those who are fully vaccinated are eight to 10 times less likely to have blood clots than those who contract COVID-19. 

Watch this: COVID-19 vaccines and blood clots explained

What should I do if I already got the Johnson & Johnson vaccine?

One of the commonalities found among those who had blood clots after taking the vaccine was that symptoms became present within six to 13 days after the shot. If you have severe headaches, difficulty breathing, stomach pain, chest discomfort or leg pain within three weeks of the vaccine, contact your doctor immediately or go to the nearest emergency room.

Is it still safe to get the Johnson & Johnson shot if it's offered?

Of the 7.2 million who received the Johnson & Johnson/Janssen vaccine, 15 developed blood clots. The risk is about 7 per million in women under 50, and lower for everyone else. But it's ultimately up to you to determine if you're willing to get the Johnson & Johnson vaccine if it's still being offered in your area.

If you have any concerns about the Johnson & Johnson vaccine or any other COVID-19 vaccine, consult with your doctor to see which shot is best for your health concerns. Keep in mind that other COVID-19 vaccines like Pfizer and Moderna have not raised the same blood clot concerns

What's going to happen with the Johnson & Johnson vaccine?

The CDC and FDA recommended a halt on the Johnson & Johnson vaccine until they could review the findings from the six clotting cases. CBS News reports the panel did not vote to extend the halt last week, as they did not have enough information to make a ruling either way. Dr. Anthony Fauci, the chief medical officer to President Joe Biden, said the panel could decide whether to resume the use of the vaccine later this week. As of April 23, the vaccine is once again in use.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.