Home Brands Pfizer COVID-19 Vaccine Tied to Blood Clotting – Is it true?

Pfizer COVID-19 Vaccine Tied to Blood Clotting – Is it true?


Medical technology such as the latest mRNA vaccines has never in history been prescribed so early as to the onset of disease transmission. Initially, only Johnson and Johnson along with AstraZeneca were reported for causing blood clots. But recent FDA reports put the claim that Pfizer Vaccines cause blood clotting too What are we dealing with exactly? Are the claims of Pfizer COVID-19 Vaccine-induced Blood Clotting true?

What is blood clotting in general?
Blood Clotting
Blood Clotting imagined in graphics, image courtesy of news-medical.net
  • Blood clotting is a medical condition in which the red blood cell becomes too thick, causing a certain clot to form. Sometimes gathered cross-mesh of fibrin protein also causes similar clots.

Blood Clotting can be deadly when it stops the proper flow of blood to the primary organs, including the heart. As such it usually leads to strokes or heart attacks.

The observed risks of blood clotting via different vaccines by companies
  • Ever since the eruption of vaccines, there have been few observed cases of the vaccines causing blood clotting. Such cases usually result in death via heart attacks. Towards the end of February 2021, reports emerged of these rare cases of blood clotting which are medically called “Thromboses”.

The clotting blocks the veins or arteries. Such effects were first observed in AstraZeneca Covid-19 Vaccines and then in the Johnson and Johnson vaccines.

What about Pfizer vaccines?
  1. On April 2021, the FDA included the risk of blood clotting within the vaccine labels. Although no properly established study has been done on Pfizer vaccines.
  2. But given the nature of the vaccines of  J&J, Pfizer, and AstraZeneca (mRNA), one might be pestered to ask if Pfizer Vaccines cause blood clotting as well.

Are Pfizer Vaccines causing Blood Clotting?

Pfizer Vaccines Cause Blood Clot
Image retrieved from wikipedia

Before the Pfizer vaccines were released, they went through the normal rigorous procedure of trials. The Pfizer trials followed 50,000 people from July to mid-November in 2022. The trials were not enough to produce concrete data on how the vaccines induced antibodies affected the human body in the long run.

  1. Pfizer vaccines, along with most others (like Johnson and Johnson) needed to be released in a hurry. This was to prevent the possible devastation that can be caused by the possible outbreak of Covid-19 in large amounts. Which anyway continued to happen.
  2. The Pfizer trials could not detect the side effects that might appear in a hundred thousand or million people. Firstly because they concluded the trials in the most minimal time. Secondly, few test subjects don’t always give a picture of how it would affect millions in the population.

Pfizer Vaccines were reported in the past to be more likely to cause Myocarditis than Blood Clotting

But as time has progressed, scientists have continued research on vaccines. The latest peer-reviewed studies prove that there could be some serious side effects via the mRNA vaccines. The kind which Pfizer Vaccines are. It could cause a certain kind of heart inflammation called myocarditis.

The risk reportedly is observed within males in their teens and 20 as per Amesh Adalja. Hence, Adalja says that he would prescribe a patient a J&J vaccine if the patient had a chance of developing myocarditis.

Pfizer Vaccines have comparatively lesser chances of causing blood clotting than other vaccines 

Bill Gates and WHO Chairperson, Pfizer Vaccines COVID-19 Cause Blood Clotting
Bill Gates and WHO’s Director General Dr. Tedros, image courtesy of World Health Organization

The Pfizer-BioNTech vaccination program in U.K Beganon on December 8, 2020. The program studied the elderly, the medically vulnerable, and those with chronic diseases such as diabetes or high blood pressure. 51% of the study were female, 79% white, and 84% were under 70 years.

  1. They compared the incidences of thromboses (Blood clotting) before and after the first dosage of the vaccine. They found that the risk of blood clotting was lower in the 28 days after the first dose of either AstraZeneca or Pfizer-BioNTech compared to before they were vaccinated.

A recent FDA Pfizer Vaccines study shows otherwise

According to the U.S. Food and Drug Administration (FDA) recently, Pfizer’s COVID-19 Vaccine is linked with causing blood clotting. The report reports that clotting occurs primarily in observed elderly patients. A form of clotting in the lungs met the threshold of providing a statistical signal that links it to Pfizer Vaccine dosages.

pulmonary embolism—blood clotting in the lungs—met the initial threshold for a statistical signal and continued meeting the criteria after a more in-depth evaluation. Researchers figured out data that included over 17.4 million elderly Americans who got their vaccine dosages between December 10, 2020, and Jan. 16, 2022.


So the immediate conclusion feels like – per FDA Pfizer vaccine reports, yes they do cause blood clotting. But both Johnson and Johnson and AstraZeneca were reported to cause thromboses in the initial reports of early 2020. The reports that we mentioned above also only studied the patients for a very numbered period of time.

  1. But the larger crux of this argument feels like this: health complicacy is usually, well complicated. A general example is that higher cigarette smoking is linked to an increased risk of cancer.
    1. But such increased risk is not definitive that one will have cancer. The causes of cancer can be numerous, including it being genetic. As such, we have to account that other causes than the vaccines could be leading to blood clotting.
  2. And at the same time, we have to be open to the idea that the vaccine itself could be a prime cause. Only then could we proceed towards better medical technologies that will learn from their mistakes.
    1. Almost the entirety of the history of pharmaceutical drugs is based on trials and errors. It is unsound logically, to think that the results of vaccines from the initial trials in 2020 are definitive for a lifetime.
SOURCES: The research paper on covid 19 vaccine causing blood clotting in the elderly TheWashingtonPost, PopSugar, MedicalNewsToday

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Rhytham is a Philosophy graduate who founded a state-level organization that promotes anime and Japanese culture in his home state in India. He is also an ardent writer, poet, musician, vocalist, graphic designer, and photoshop artist. He has worked on multiple state and national level conventions. Other than anime, catch him watching western series that really have in themselves the solidity to catch his attention.