A group of German scientists led by Professor Andreas Greinacher at the University of Greifswald in a statement said they believe the AstraZeneca shot prompts an overactivation of platelets in the blood. This leads to the development of potentially deadly clots.

Greinarcher’s team analyzed 13 cases of cerebral blood clots reported in Germany. The analysis involved 12 women and 1 man who developed blood clots between four and 16 days after inoculation. The researchers were able to isolate and identify the antibodies that caused the overactivation of the platelets.