Blood Clots after Oxford Vaccine

Subject – Science and Tech

Context – Study finds mechanism of blood clots after giving Oxford vaccine

Concept –

The journal Science Advances has revealed for the first time the mechanism responsible for blood clots arising from thrombosis with thrombocytopenia syndrome (TTS) following vaccination with AstraZeneca vaccine.
Thrombocytopenia syndrome causes low platelet count.
A low number of platelets – blood cells that help prevent blood loss when vessels are damaged – can result in no symptoms or can lead to an increased risk of bleeding or, in some cases, clotting.
Thrombosis with thrombocytopenia syndrome is a very rare serious adverse effect following vaccination using chimpanzee adenovirus Y25 (ChAdOx1), human adenovirus type 26 (HAdV-D26), and human adenovirus type 5 (HAdV-C5).
AstraZeneca vaccine and the Indian counterpart Covishield use the chimpanzee adenovirus Y25, while Johnson & Johnson vaccine uses the human adenovirus type 26.
- The Sputnik vaccine uses both human adenovirus type 26 and human adenovirus type 5 as vectors to ferry the spike protein into certain cells.
The researchers found that all three adenoviruses used in a few COVID-19 vaccines as vectors bind to platelet factor 4 (PF4). They found that adenoviruses form stable complexes with PF4.

What is Thrombosis?

Thrombosis is the formation of a blood clot, known as a thrombus, within a blood vessel. It prevents blood from flowing normally through the circulatory system.
Blood clotting, also known as coagulation, is the body’s first line of defense against bleeding. When we hurt ourselves, our clotting system forms a “plug” or “seal” to protect us from losing too much blood.
Our bodies often break down the clot after we’ve healed – but sometimes, clots form inappropriately or fail to dissolve after an injury. A blood clot that forms and stays in a blood vessel is called a thrombus.
Other medical terms used to describe blood clots include:
- Thrombosis: When a thrombus forms in a blood vessel.
- Embolus or Embolism: A clot that detaches and travels through blood vessels to another part of the body.