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Vaccine-induced immune thrombotic thrombocytopenia

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 World Health Organization (WHO 2023) and the American Society of Hematology (ASH 2022).
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Guidelines

1.Screening and diagnosis

Diagnostic criteria: 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)
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  • Differential diagnosis

2.Classification and risk stratification

Vaccine-related risks: 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.
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3.Diagnostic investigations

Laboratory tests: obtain urgent evaluation for VITT if any of the following develop 4-30 days after vaccination:
severe headache
visual changes
abdominal pain
nausea and vomiting
back pain
shortness of breath
leg pain or swelling
petechiae, easy bruising, or bleeding
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  • Diagnostic imaging

4.Medical management

Anticoagulation and IVIG
As per WHO 2023 guidelines:
Initiate anticoagulation in all patients presenting with VITT following COVID-19 vaccination.
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Initiate IVIGs or non-heparin-based anticoagulants in patients with VITT following COVID-19 vaccination,
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Consider initiating heparin for anticoagulation if non-heparin anticoagulants are not available.
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  • Corticosteroids

  • Aspirin

5.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.
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  • Plasma exchange

6.Follow-up and surveillance

Indications for referral
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.
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Consider referring patients with confirmed VITT to a tertiary care center.
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