A German team of researchers this week said they may have discovered what causes rare blood clots in some COVID-19 vaccine recipients. Rolf Marschalek, a professor at Goethe University in Frankfurt who has been involved in studies looking into the rare clotting condition caused by the Oxford-AstraZeneca vaccine, said his researcher showed the issue may be triggered due to adenovirus vectors. An adenovirus—a common cold virus that can’t replicate—is the primary mechanism used by both the AstraZeneca and Johnson & Johnson vaccines, delivering the genetic instructions for the spike protein of the virus into the recipient’s body. Meanwhile, vaccines made by AstraZeneca and Pfizer use mRNA technology. The German scientists led by Marschalek said in a research paper that hasn’t yet been peer-reviewed that the problem might be caused when the adenovirus enters the nucleus of the cell rather than the cellular fluid, where the virus makes proteins. “The adenovirus life cycle includes …