Study shows how COVID vaccines may cause blood clots in rare cases

Researchers led by Flinders University have suggested why a rare blood clotting disorder can occur in some people after certain COVID-19 vaccines or adenovirus infections. In extremely rare cases, the immune system can mistakenly confuse a normal adenovirus protein with a human blood protein called platelet factor 4 (PF4). This triggers the body to produce antibodies that activate blood clotting.