A team of German scientists claim they have identified the reason some people have developed blood clots after receiving certain coronavirus vaccines. According to the scientists, the vaccines can be redesigned to avoid the unwanted side-effect.

Frankfurt professor knows how to prevent vaccine blood clots

In recent months, the AstraZeneca and Johnson & Johnson vaccinations have been plagued by reports of blood clots developing in patients. This has caused massive delays to Germany’s vaccination drive against coronavirus. However, a team of German scientists believe they may well have identified the cause of these blood clots, and figured out how to prevent them from occurring.

Rolf Marschalek, a professor at Goethe University in Frankfurt, explains that the connection between the vaccines and the blood clots lies in the entry of the adenovirus, the common cold virus that delivers the coronavirus spike protein. Other coronavirus vaccines, such as the mRNA vaccines developed by Moderna and Pfizer / Biontech, do not use this delivery method and have not had links to cases of blood clotting.

The science behind the blood clots

In a research paper that still has to undergo peer review, the scientists claim that the problem with certain vaccines is due to the delivery of the adenovirus into the nucleus of the cell, instead of the cellular fluid where the virus usually makes proteins.

“The adenovirus life cycle includes the infection of cells… entry of the adenoviral DNA into the nucleus, and subsequently gene transcription by the host transcription machinery,” the scientists wrote. “And exactly here lies the problem: the viral piece of DNA… is not optimised to be transcribed inside of the nucleus.” Essentially, the scientists believe that parts of the spike protein break off inside the nucleus of the cell, which can then be transported around the body and, in rare cases, cause blood clots.

However, as previously mentioned, it is important to note that the scientists' work has not been reviewed by other scientists, doctors and experts, meaning that their work is still only considered a hypothesis.

Developing a better coronavirus vaccine

Marschalek told reporters that representatives from Johnson & Johnson have already been in touch with the company, reportedly trying to redesign and optimise their vaccine. "With the data we have in our hands we can tell the companies how to mutate these sequences, coding for the spike protein in a way that prevents unintended splice reactions,” said Marschalek.

Marschalek told reporters that he hadn’t been in touch with AstraZeneca yet but said if he spoke to the international company, he could tell them “what to do to make a better vaccine.”