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COVID Vaccines and Rare Blood Clot Risks

Verified By Apollo Pulmonologist April 24, 2021 17517 0
Covid Vaccines & Rare Blood Clots
Covid Vaccines & Rare Blood Clots

COVID-19 began in the latter half of December 2019 only to turn into a pandemic. Countries have started massive vaccination drives and some started reporting a few cases of rare blood clots due to vaccination. For example, six individuals from among the nearly seven million vaccinated by the Johnson & Johnson vaccine experienced  blood clots post-vaccination. This caused the authorities to place the vaccination drive on hold temporarily. The Oxford-AstraZeneca vaccine, too, faced the same problem. Similar cases were seen for various other vaccines administered worldwide.

The vaccine’s use and administration without fear in the coming days calls for proper information regarding its efficacy.

You can consult with your doctor in detail about this.

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Some of the critical questions that can help resolve the confusion are:

What is the connection between vaccines and the development of rare blood clots?

Blood clots have been primarily linked to the Johnson & Johnson and the Oxford-AstraZeneca vaccines. The key characteristics of the clots are their occurrence in unusual parts of the body, such as the abdomen or blood clot in the brain, cell fragmentation progressing to blood coagulation, and decreased platelets in the blood. Both the vaccines from Johnson & Johnson and the Oxford-AstraZeneca are adeno vector vaccines. They direct the human cell machinery to manufacture the spike protein so that the body can develop an immune response against it. Ongoing research aims to determine the specific segment of the vaccine that causes blood clots.

Some patients who had this complication had unusual antibodies to platelet factor 4, a signaling protein which helps our body coordinate blood clotting. The presence of antibodies suggests that the vaccines are in someway triggering autoimmune attack which causes to form large clots that then diminish the supply of platelets in our blood.

Would all other vaccines also result in such rare blood clots?

Both the Johnson & Johnson and the Oxford-AstraZeneca vaccines are adenovirus-based vaccines. The same applies to Sputnik V, a Russian vaccine. Despite the disclaimer from the Russian scientists stating there are no side effects, including blood clots in their vaccines, various laboratories worldwide are waiting to observe any damage to the vascular system upon administration for the adenoviral-based vaccines. The trigger point could be with the adenovirus itself, the spike protein, or any contaminant, and determining this can help shape the future of vaccines.

How rare are the blood clots among vaccinated individuals?

It is evident to the researchers that the risk of clots is  very low, with approximately eighty-six individuals who developed  clotting compared to the twenty-five million who were vaccinated in Europe.

Are certain groups of people more at risk than others?

As of now , it is difficult to determine if any age or medical group is at more risk than others. Various reports suggest that increased risk for women and young recipients is misleading since most healthcare workers has a preponderance of  young women.

Therefore, the right information is essential to identify the risk factors that make an individual more prone to blood clots than others, and they also need to be analyzed , weighed against the risks of COVID-19.

While serious side effects are extremely rare, if you feel any of the following from the first four days to four weeks following the vaccination you should seek medical advice immediately.

  • A new, severe headache that has not gone away with the usual  painkillers or is getting worse
  • A headache that seems worse while bending over or lying down
  • An unusual headache which could be accompanied by:
  • – difficulty with your speech

– blurred vision, nausea and vomiting

– weakness, drowsiness or seizures

  • New, unexplained pinprick bleeding or bruising
  • Chest pain, shortness of breath
  • Persistent abdominal pain
  • leg swelling


Many researchers point out that the vaccination drives across countries are closely monitored, and therefore, can report such rare events. But mixed reports about the different types of vaccines, technical discussions about the risks, and the medical conditions confuse the masses. It is necessary not to let the public develop a feeling of mistrust. Various governing bodies can take up responsibilities to curtail media that falsify and spread fear among people. Instead, they should encourage the media certified to impart the right educational information to educate people regarding vaccination, its potential risks, and the current statistics.

Therefore, it is necessary to be aware and be made aware. In the fight against COVID-19, we all must do our part and stand as a united front, and that majorly includes not being confused and spreading confusion.

Frequently Asked Questions (FAQs)

  1. What are the other types of COVID-19 vaccine?

Primarily, there are four types of COVID-19 vaccines available globally. These are Inactivated whole virus (whose genetic make has been destroyed to prevent infection and replication), Subunit vaccines (contains fragments of the virus to trigger an immune response), Nucleic acid (messenger RNA-based vaccines), and Viral vector vaccines (which transport instruction to the human cell via another innocuous virus ,  to generate an immune response).

  1. What are the signs and symptoms of a blood clot?

You will notice the following symptoms if you develop a blood clot. These are pulsating headaches and throbbing sensations in the head, breathlessness, chest pain, seizures, pain in the abdomen and legs, and high blood pressure. It is advised to immediately consult with your doctor if you experience any such symptoms.

  1. Are the vaccines effective against the variants?

Some reports from various clinical trials suggest that the vaccines have shown effectiveness against the new strains, especially the B.1.1.7 variant, predominantly found in the UK. Studies are underway regarding the effectiveness of the vaccines against various other strains as well.

  1. One of my family members had a blood clot. Should I still get vaccinated?

Of course. You must still get vaccinated to prevent contracting the infection.

Verified By Apollo Pulmonologist

The content is verified and reviewd by experienced practicing Pulmonologist to ensure that the information provided is current, accurate and above all, patient-focused

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