Polish experts explain possible causes of thrombosis after COVID-19 viral vector vaccine

Thrombosis caused by COVID-19 viral vector vaccines are very rare. Polish scientists discuss possible causes in the scientific journal titled “Vaccines”.

“Thromboembolic reactions have also been reported with mRNA vaccines. With such a low incidence, clinical trials simply cannot catch them. Nevertheless, the causes of these events require clarification," Piotr Rzymski, expert in the field of medical biology and research at the Karol Marcinkowski University in Poznań said.

“It is clear to us that whatever leads to thromboembolic events after vaccination has to be highly specific, requires appropriate circumstances and perhaps might be caused by certain genetic conditions,” the scientist added.

Thromboembolic events after the COVID-19 vaccine might be caused by a component of the vaccine forming a heparin/platelet factor 4 (PF4) complex which, in turn, would cause the body to develop antibodies against it. Another reason might be the direct interaction of the viral vector adenovirus with platelets.

“It is possible that thrombosis and the accompanying thrombocytopenia following the administration of the COVID-19 vaccine are of a multifactorial nature. Certainly, the occurrence of such events is limited to specific circumstances and conditions, which makes them extremely rare,” Mr Rzymski emphasised.

In this context, it is worth remembering two important issues. “First of all, the benefits of the COVID-19 vaccine significantly outweigh the potential risks associated with vaccination. Secondly, COVID-19 is the major factor that increases the risk of thrombosis and its serious consequences. By vaccinating, we protect ourselves against the insidious effects of the virus and the way the infection affects our body," the scientist said.

He added that the authors of the publication hope that some of the mechanisms discussed in the article will be undertaken by other research groups and that together they will find out the causes of thromboembolic events and identify the group of people who are at risk of their occurrence. "This is how science works, we inspire each other and complement each other in order to find solutions to particular problems," Mr Rzymski concluded.