AstraZeneca Vaccine Blood Clots : What To Look For?

Some people, including a Brisbane nurse, developed blood clots from the AstraZeneca vaccine – a rare complication.

Find out what you should look out for, after getting vaccinated against COVID-19 using the AstraZeneca vaccine!


AstraZeneca Vaccine Blood Clots : What Are They?

Scientists are now quite certain that the AstraZeneca vaccine can induce a rare side effect with a variety of names :

  • Thrombosis with Thrombocytopenia Syndrome (TTS)
  • Vaccine-induced Thrombotic Thrombocytopenia (VITT) or even
  • Vaccine-induced Prothrombotic Immune Thrombocytopenia (VIPIT).

In a very small number of cases, the AstraZeneca vaccine can trigger the immune system to create anti-PF4 (Anti-Platelet Factor 4) antibodies.

These anti-PF4 antibodies attack the platelets, causing them to clump together and blood clots to form.

This creates a situation where the person not only develops blood clots, but also has low platelets. The risk is not zero, but it is exceedingly rare.

Recommended : AstraZeneca Vaccine Blood Clot Risk : How Dangerous Is It?


AstraZeneca Vaccine Blood Clots : How Dangerous Are They?

These blood clots are a little unusual in that they can develop in the large veins of the brain and/or abdomen and/or lungs, and are coupled with low platelet counts, leading to bleeding tendencies.

In May 2021, the Australian Therapeutic Goods Administration (TGA) confirmed that Ellie Peacock – a trainee nurse in Brisbane – suffered TTS, developing three blood clots in her lungs. Ms. Peacock has since recovered from TTS.

The good news is now that we know about this rare risk factor, we can look out for these blood clots and treat them before complications develop.

As of 30 June 2021, 64 people in Australia developed TTV, out of 4.2 million doses administered. Only 2 have died so far.


AstraZeneca Vaccine Blood Clots : What To Look For?

People who develop these blood clots will complain of these symptoms 4 to 30 days after receiving the AstraZeneca vaccine :

  • Severe headache that
    does not improve with simple painkillers (like paracetamol / acetaminophen)
    gets worse when lying down
  • Neurological changes
    – blurred vision
    – speech difficulties
    – drowsiness
    – seizures
  • Nausea and vomiting
  • Persistent abdominal pain
  • Back pain
  • Shortness of breath
  • Leg pain or swelling
  • Petechiae (tiny blood spots under the skin)
  • Easy bruising or bleeding

If you notice any of these symptoms after receiving the AstraZeneca vaccine, DO NOT WAIT. Seek medical attention right away!

The earlier you seek medical attention, the less likely you will develop complications. Please do NOT self-medicate with painkillers.

If you need to take painkillers for post-vaccination fever / headache, avoid aspirin, as it can exacerbate the bleeding tendency with TTS.

Take paracetamol (acetaminophen) instead. If they do not help, you could have TTS.


AstraZeneca Vaccine : Why Risk The Blood Clots?

It is understandable to worry about blood clots and bleeding tendencies. They are serious and should not be dismissed out of hand.

However, we must keep in mind that the risk of being hospitalised and dying from COVID-19 is much, MUCH HIGHER than the risk of developing blood clots from the AstraZeneca vaccine.

These two charts show the risks of hospitalisations (left) and death (right) from COVID-19 (blue) and TTS (red).

As you can see, the risk of hospitalisation and death is incredibly skewed towards COVID-19.

In a perfect world where you have ready access to alternative vaccines, it makes sense to be extra cautious and avoid even these few cases of blood clots with bleeding tendencies.

You can see some countries opting to do that, out of an abundance of caution. Why risk even such a minute risk, if you have plenty of alternative vaccines?

However, COVID-19 vaccines are in very short supply in most countries. It will be months before alternative vaccines from Pfizer, Moderna, etc. are available.

Should you wait until an alternative COVID-19 vaccine arrives? That is generally not a good idea, because vaccines only work if you get them BEFORE you are infected.

The best COVID-19 vaccine is the FIRST COVID-19 vaccine you can get and complete.

I highly recommend that you accept the first COVID-19 vaccine you are offered, be it AstraZeneca or Pfizer or even Sinovac, and complete the dosage requirements to protect yourself at the earliest possible opportunity.

If it so happens you receive the AstraZeneca vaccine, simply take note of the potential symptoms of TTS above, and seek medical attention if you identify any of them.


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Dr. Adrian Wong has been writing about tech and science since 1997, even publishing a book with Prentice Hall called Breaking Through The BIOS Barrier (ISBN 978-0131455368) while in medical school.

He continues to devote countless hours every day writing about tech, medicine and science, in his pursuit of facts in a post-truth world.


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