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Vaccine-induced immune thrombotic thrombocytopenia

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Updated 2023 WHO and 2022 ASH guidelines for the diagnosis and management of vaccine-induced immune thrombotic thrombocytopenia.

Guidelines

Key sources

The following summarized guidelines for the evaluation and management of vaccine-induced immune thrombotic thrombocytopenia are prepared by our editorial team based on guidelines from the International Society on Thrombosis and Haemostasis (ISTH 2024), the World Health Organization (WHO 2023), and the American Society of Hematology (ASH 2022). ...
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Screening and diagnosis

Diagnostic criteria: as per ASH 2022 guidelines, diagnose VITT if all 5 criteria are MET:
COVID-19 vaccine 4-42 days before symptom onset
any venous or arterial thrombosis (often cerebral or abdominal)
thrombocytopenia (platelet count < 150×10⁹/L)
positive PF4 ELISA (heparin-induced thrombocytopenia assay)
markedly elevated D-dimer (> 4 times the ULN).
E
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  • Differential diagnosis

Classification and risk stratification

Vaccine-related risks: as per ASH 2022 guidelines, recognize that the incidence of VITT is extremely low, and the risk of death and serious outcome of COVID-19 infection, including thrombosis, far outweigh the risk of VITT possibly associated with highly efficacious vaccines.
E

Diagnostic investigations

Laboratory tests
As per ISTH 2024 guidelines:
Obtain antiplatelet factor 4 enzyme immunoassays for diagnosis in patients with suspected VITT.
B
Do not obtain rapid heparin-induced thrombocytopenia assays, such as particle gel immunoassay, lateral-flow assay, latex-enhanced immunoturbidimetric assay, or chemiluminescence immunoassay, in patients with suspected VITT.
D

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  • Diagnostic imaging

Medical management

Anticoagulation and IVIG
As per ISTH 2024 guidelines:
Consider initiating UFH or LMWH to reduce the risk of adverse outcomes in patients with vaccine-induced thrombotic thrombocytopenia if a non-heparin anticoagulant is unavailable.
C
Consider initiating IVIG to reduce the risk of death in patients with vaccine-induced thrombotic thrombocytopenia.
C

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  • Corticosteroids

  • Aspirin

Therapeutic procedures

Platelet transfusion: as per WHO 2023 guidelines, do not administer platelet transfusion in patients presenting with VITT following COVID-19 vaccination unless in emergency situations when surgery is required, thrombocytopenia is severe (< 50×10⁹ platelets/L), and the patient is bleeding, or platelet transfusion is required to be able to proceed with emergency surgery.
D

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  • Plasma exchange

Follow-up and surveillance

Indications for referral
As per ASH 2022 guidelines:
Obtain urgent consultation with a hematologist with expertise in hemostasis for patients with thrombocytopenia or thrombosis. Avoid using heparin until VITT has been excluded or until an alternative other plausible diagnosis has been made.
E
Consider referring patients with confirmed VITT to a tertiary care center.
E