In late January, the first suspicions arose that the AstraZeneca vaccine could be linked to rare cases of blood clot formation. Blood clots are a natural physiological response of the human body, which helps to control bleeding or bleeding.
The European Medicines Agency (EMA) has commented on the side effects of the vaccine, stating that the reported combination of blood clots and low blood platelets is very rare. The EMA stressed that the overall benefits of the vaccine in preventing Covid-19 outweigh the risks of side effects.
In April, the World Health Organization (WHO) also issued a statement stating that a new type of adverse event called Thrombosis with Thrombocytopenia Syndrome (TTS), involving unusual and serious blood clotting events associated with low platelet counts, was reported after vaccination with AstraZeneca.
What explains the formation of rare clots
Scientists may have found the decisive factor for the formation of rare blood clots after vaccination with AstraZeneca. A study, conducted by researchers in the United States, revealed that a protein present in the blood can be attracted by one of the components of the immunizing agent.
As a result, the reaction involving the immune system can lead to the development of clots. The study was published in the journal Science Advances on Wednesday (1).
Extremely rare side effects have emerged during massive vaccination campaigns around the world and are not seen in phase 3 studies that take place during vaccine development.
These rare adverse effects include Thrombosis with Thrombocytopenia Syndrome (TTS), a rare condition similar to heparin-induced thrombocytopenia (HIT), a serious complication of heparin anticoagulant therapy associated with clot formation.
The study showed that adenoviruses used as vectors in the AstraZeneca vaccine bind to a protein called platelet factor 4 (PF4), which is associated with the development of heparin-induced thrombocytopenia.
The research used computer models to determine the structure of the adenovirus and demonstrate the mechanism of interaction with the PF4 protein, which was confirmed experimentally by a type of resonance.
Reference: CNN Brasil