Box 1.

Criteria for a diagnosis of vaccine-induced prothrombotic immune thrombocytopenia (VIPIT)

  • Onset 5 to 30 days post-vaccination

  • Thrombocytopenia

  • Presence of thrombosis

  • D-dimer >2,000 ng/mL

  • Positive anti-PF4 antibodies on ELISA

  • All five criteria are met = ‘definite’ diagnosis of VIPIT.