RELATED: If You Have This Blood Type, You’re More Likely to Get Blood Clots. Blood expert Andreas Greinacher, MD, believes that he has identified what’s causing blood clots in Johnson & Johnson and AstraZeneca recipients, according to The Wall Street Journal. Greinacher, along with his team at the University of Greifswald, published a study on April 9 in The New England Journal of Medicine. The team proposed that viral vector vaccines, which use modified viruses to transfer genetic material via vaccination, could result in an autoimmune response that provokes blood clots. The Johnson & Johnson and AstraZeneca vaccines are both viral vector vaccines, while the Pfizer and Moderna vaccines are mRNA vaccines that work using different mechanisms.ae0fcc31ae342fd3a1346ebb1f342fcb According to Science Magazine, Greinacher and his team believe that the blood clots could be linked to stray proteins and a specific preservative. While they only just began studying Johnson & Johnson’s vaccine, they have made significant discoveries regarding the AstraZeneca vaccine, which is very similar to Johnson & Johnson. Per The Wall Street Journal, the team has observed more than 1,000 proteins in the vaccine that are derived from human cells. Researchers also found the preservative ethylenediaminetetraacetic acid (EDTA) in the vaccine, which could be the key to understanding the blood clots. Greinacher hypothesizes that the EDTA helps proteins from human cells stray into the bloodstream—once there, they bind to a component of blood called platelet factor four. The inflammation that can come from the vaccine, combined with the platelet factor four, could confuse the immune system, making it think the body has been infected. This, in turn, can trigger an “archaic defense mechanism that then runs out of control and causes clotting and bleeding,” The Wall Street Journal reports. Greinacher has compared this reaction to “awakening a sleeping dragon.”

RELATED: For more up-to-date information, sign up for our daily newsletter. While more research needs to be done to understand the complexities of the blood clots that follow vaccination, these findings can help point researchers in the right direction. Finding the precise reason these rare blood clots are occurring is necessary to help vaccine recipients and health experts make risk assessments and deliver care. Additionally, figuring out what causes the blood clots can help inform future vaccines. “Understanding the cause is of highest importance for the next-generation vaccines because [the novel] coronavirus will stay with us and vaccination will likely become seasonal,” Eric van Gorp, PhD, a professor at Erasmus University in the Netherlands, told The Wall Street Journal. To continue learning more about the connection, a Johnson & Johnson spokesperson told The Wall Street Journal that the company is looking into a potential collaboration with Greinacher. RELATED: If You Take This Medication, You’re More Likely to Get a Blood Clot.