COVID Vaccine and Blood Clots

-Dr. Sanoop Kumar Sherin Sabu M.D. (Int Med), FCPM, Institutor And Specialist In Lifestyle Disease Screening

COVID Vaccine and Blood Clots

I have been receiving phone calls from my relatives and concerned patients regarding the recent news about AstraZeneca has accepted a link between the vaccine and Thrombosis with Thrombocytopenia Syndrome (TTS). Concerned calls are mostly from people who have previously taken COVISHIELD vaccine.

But what is fact?

  • As per available literature percentage of reported cases of Blood clots caused by the vaccination till date (May 2024) is 000003 to  0.000061 %.  (1)
  • Most importantly, the percentage of people who developed Blood clots following a COVID infection in is as high as 26% , which is 4,00,000 (4 lakhs) times more than what vaccine against COVID can cause.  (2)
  • More interestingly, this fact regarding Thrombosis with Thrombocytopenia Syndrome (TTS) or VITT (Vaccine Induced Thrombocytopenic Thrombosis) is not something new. It was already made clear by the vaccine company as a possible rare side effect in way back 2021 itself (3)

Therefore, being vaccinated by COVISHIELD should not make you worried when you hear the news that spreads around. Rather a previous COVID infection is having more chances of blood clots inside you. So vaccine which have prevented development of severe COVID Infection, is an indirect protection for you in some sense.

What can you do?

Visit your physician and evaluate yourselves if you have any of the below: –

  • Deep pain in the calf muscles
  • Sudden onset breathing difficulty
  • Weakness or inability to use your hands or legs
  • Slurring of speech
  • Chest pain

Your physician, after a detailed examination and assessment of your risk, will do the needful investigations to evaluate if you have any blood clots.

How do we diagnose TTS?

  • Clinical features
  • Vaccine history
  • Low platelet count, elevated D-Dimer Levels, low or normal fibrinogen level
  • Scans/imaging to prove blood clots 


Not all blood clots are caused by COVID INFECTION or COVISHIELD vaccine. Even before 2020, people have had blood clots due to other reasons like diabetes, smoking, cancer, high blood cholesterol, dehydration, alcoholism, rare genetic diseases.

I have personally seen more number of deaths due to COVID-19 infection causing complications like blood clots than COVID Vaccine resulting in blood clots. Yes, reports of rare incidence of blood clots caused following vaccination is there. But that should not create fear in you.

Therefore, quit smoking, abstain from alcohol, drink plenty of water, keep your sugars and other health conditions under good control.. This can help you remain safer than being anxious


  2. Cheng NM, Chan YC, Cheng SW. COVID-19 related thrombosis: A mini-review. Phlebology. 2022 Jun;37(5):326-337. doi: 10.1177/02683555211052170. Epub 2022 Apr 10. PMID: 35403487; PMCID: PMC9006089.

Dr. Sanoop Kumar Sherin Sabu
M.D. (Int Med), FCPM,
Institutor and Specialist in Lifestyle Disease Screening

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