PF4 and Arterial thrombosis: VITT/VIPITT is defined as presence of venous or arterial thrombosis, thrombocytopenia, and autoantibodies (anti-PF4–polyanion or anti-PF4–heparin antibodies) within 5–30 days of vaccination with either AstraZeneca or Janssen/Johnson & Johnson COVID-19 vaccines (147).