Two studies today in the New England Journal of Medicine describe 11 patients in Austria and Germany and 5 in Norway who developed an unusual blood clotting disorder after receiving their first dose of the AstraZeneca/Oxford COVID-19 vaccine.Clots form in brain, abdomenThe first study, led by researchers at the Institute for Immunology and Transfusion Medicine in Greifswald, Germany, involved 11 patients who had abnormal blood clots or thrombocytopenia (low platelet counts) 5 to 16 days after receiving the AstraZeneca vaccine.One patient had a fatal intracranial hemorrhage (bleeding in the brain), while nine had cerebral venous thrombosis (blood clots in the brain), three had splanchnic vein thrombosis (blood clots in abdominal veins),