COVID-19 Vaccines and Blood Clots 

  • IASbaba
  • April 19, 2021
  • 0
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COVID-19 Vaccines and Blood Clots 

Part of: GS Prelims and GS – III – Sci & tech 

In news

  • Reports of rare blood clots occurring after COVID-19 vaccination have led some countries to limit the usage of AstraZeneca’s vaccine for certain categories of people, while other countries have paused the administration.

Key takeaways 

  • An adverse effect following immunisation with the AstraZeneca jab is not merely blood clots in large vessels, but also a low platelet count.
  • The effect is similar to heparin-induced thrombocytopenia (HIT), where heparin, which is used to clear clots, actually causes blood clots and a fall in the platelet count.
  • The heparin combines with platelet factor 4 to form a complex. 
  • This immune complex induces an abnormal immune response, in which antibodies are generated against the complex.
  • This antibody-platelet factor 4-heparin immune complex binds to platelets and activates them. 
  • The platelets form clots everywhere. 
  • The low platelet count is because the platelets are used up.
  • A similar process seems to follow vaccination, except there is no heparin trigger.
  • Scientists are still trying to establish a clinical definition for this adverse effect.

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