Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but potentially serious adverse reaction that has been reported following vaccination with certain COVID-19 vaccines. It is characterized by the formation of blood clots in small blood vessels, combined with a low platelet count (thrombocytopenia). Symptoms of VITT may include shortness of breath, chest pain, leg swelling, skin discoloration, abdominal pain, and neurological symptoms such as confusion or difficulty speaking. The exact cause of VITT is not fully understood, but it is known to be mediated by the formation of anti-PF4 antibodies which cause platelet activation via FcyRIIA. Note that while the diagram shows that antibodies against the spike protein, data suggests it is antigens within the vector (ChAdOx1 or Ad26-CoV-2S) that generate anti-PF4 antibodies #VITT #Vaccine #Induced #immune #thrombotic #thrombocytopenia #COVID #pathophysiology
