Azd-1222

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An event is serious (based on the ICH definition) when the patient outcome is:

• * death

• * life-threatening

• * hospitalisation

• * disability

• * congenital anomaly

• * other medically important event

In a study, 9 patients (7 women and 2 men) aged 21-73 years were described; all the patients developed vaccine-induced immune thrombotic thrombocytopenia (VITT), cerebral vein thrombosis, splanchnic vein thrombosis, ischemic stroke, deep vein thrombosis, pulmonary embolism or aortic thrombosis following vaccination with AZD-1222 for prevention of COVID-19 [routes and dosages not stated].

The patients received vaccination with AZD-1222 [ChAdOx1 nCoV-19; AstraZeneca] for prevention of COVID-19. After 9-18 days from vaccination, all the patients developed severe thrombocytopenia with platelet count of 9-61000/ mm³. Of the 9 patients, 8 patients also developed cerebral vein thrombosis (n=2), cerebral vein thrombosis and splanchnic vein thrombosis (n=3), ischemic stroke and deep vein thrombosis (n=1), cerebral vein thrombosis, splanchnic vein thrombosis, pulmonary embolism and deep vein thrombosis (n=1) or splanchnic vein thrombosis, pulmonary embolism and aortic thrombosis (n=1). The plasma samples of 9 patients were suspicious of VITT. Hence, two rapid immunoassays performed on plasma samples to detect PF4-specific antibodies, and results were negative in all the patients. Thereafter, the plasma samples of all the patients were tested with three different PF4-specific enzyme-linked immunosuppressant assays which showed significant levels of IgG antibodies to PF4 in seven patients. A serotonin release assay (SRA) was performed with the use of PF4 to detect platelet-activating antibodies to VITT. The diagnosis of VITT was confirmed by PF4–serotonin release assay in all seven patients with IgG antibodies to PF4–PVS, whereas a standard serotonin release assay was negative in two patients. The patients' platelet activation was not inhibited by therapeutic concentrations of unfractionated heparin 0.1 or unfractionated heparin 0.5. Platelet activation was suppressed by IV.3.