2 days ago New research has identified unusual antibodies that appear to have caused, in rare cases, serious and sometimes fatal blood clots in people who received the Covid vaccine made by AstraZeneca. Exactly why the rare reactions to the vaccine occurred is still a mystery. Scientific teams from Germany and Norway found that people who developed the clots after vaccination had produced antibodies that activated their platelets, a blood component involved in clotting. The new reports add extensive details to what the researchers have already stated publicly about the blood disorder.