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This Guidelines summary covers recommendations for identifying, diagnosing, and managing vaccine-induced immune thrombocytopenia and thrombosis (VITT).

Recommendations on identifying suspected VITT, investigations and diagnosis, management, reporting cases, and further vaccination are included in this summary.

This summary does not include NICE’s recommendations on additional considerations for treating thrombosis, further treatments, intensive treatment for people with signs of poor prognosis, further investigations for probable VITT, and monitoring response and treating relapse.

This summary only covers key recommendations for primary care. See the full guideline for a complete list of recommendations.

View this summary online at guidelines.co.uk/456202.article

Identifying suspected VITT

  • For people presenting to primary care or emergency care, or contacting NHS 111 with new or ongoing symptoms within 5–30 days of having had a COVID-19 vaccination, follow the advice from Public Health England on:

Investigations and diagnosis

  • When assessing people with suspected VITT, ask about their vaccination history
  • Take into account their overall clinical condition, and:
    • refer people who are acutely unwell to the emergency department immediately or
    • perform initial tests (full blood count) in primary care if:
      • the person is not acutely unwell and
      • same-day test results can be obtained, and if they show thrombocytopenia, the person can be referred to the emergency department immediately.

Initial investigations

  • If not already done in primary care, perform a full blood count to look for evidence of thrombocytopenia in people with suspected VITT
  • If the full blood count confirms thrombocytopenia, or a strong clinical suspicion of VITT remains, do the following tests in secondary care:
    • a coagulation screen, including Clauss fibrinogen assay and D-dimer measurement
    • a blood film to confirm true thrombocytopenia and identify potential alternative diagnoses.

When making a diagnosis of VITT, take into account that:

  • VITT is probable in people with:
    • thrombosis and thrombocytopenia with very high D-dimer and low or normal fibrinogen or
    • thrombosis and thrombocytopenia with high D-dimer and low or normal fibrinogen and strong clinical suspicion
  • VITT is unlikely in people with:
    • no thrombocytopenia
    • thrombocytopenia without thrombosis, and D-dimer at or near normal and normal fibrinogen or
    • thrombosis without thrombocytopenia, and D-dimer that is raised (but not the high and very high levels seen in VITT) and normal fibrinogen.

Further care when VITT is unlikely

  • For people whose blood tests indicate it is unlikely they have VITT:
  • If a high clinical suspicion of VITT remains, consider:
    • repeating the full blood count after 2–3 days or if symptoms worsen or
    • discuss the need for further investigations with a clinical haematologist.


Person-centred care

  • Explain to the person and their family members or carers, if appropriate, what a diagnosis of VITT means. Discuss treatments and possible outcomes; be prepared to answer any questions they might have about their care, and take into account their concerns
  • Involve a clinical haematologist when making decisions about starting and adding treatments.

Managing thrombosis


  • Start anticoagulation treatment for people with VITT, including those who have only had arterial thrombosis, as soon as the benefit outweighs the risk of bleeding
  • Review the person’s response to anticoagulation if the person’s clinical condition changes, and adjust treatment if needed
  • Use non-heparin drugs for anticoagulation treatment for VITT, for example:
    • direct oral anticoagulants
    • fondaparinux
    • danaparoid sodium
    • argatroban
  • When using argatroban as an anticoagulation treatment for people with VITT, switch to fondaparinux or a direct oral anticoagulant as soon as the bleeding risk has reduced
  • If surgery to treat the thrombosis is not planned, switch to oral anticoagulation with direct oral anticoagulants as soon as the person’s clinical condition and platelet level allows. Continue the same anticoagulation treatment after discharge
  • For people with VITT without confirmed thrombosis, but who have thrombocytopenia with very high D-dimer and a positive ELISA for platelet factor 4 antibodies, consider venous thromboembolism thromboprophylaxis after taking into account the benefits and risks of treatment. Use non-heparin drugs such as direct oral anticoagulants, fondaparinux, or danaparoid sodium, and regularly reassess whether the benefits of thromboprophylaxis still outweigh the risks throughout treatment.

For information on additional considerations for treating thrombosis and managing the VITT immune response, see the full guideline.

Ongoing management

Patient-centred care

  • Give people with VITT details of support resources such as Thrombosis UK
  • Consider referral for psychological support for people who have, or have had, VITT. Take into account that family members and carers of people with VITT may also benefit from psychological support, particularly if the person has been seriously ill, and give them information on available support services.

For information on monitoring response and treating relapse, see the full guideline.

Reporting cases

Further vaccinations

  • For people who have had suspected or confirmed VITT, follow advice on further COVID-19 vaccination in the Green Book (chapter 14a).


© NICE 2021. COVID-19 rapid guideline: vaccine-induced immune thrombocytopenia and thrombosis (VITT). Available from: nice.org.uk/ng200. All rights reserved. Subject to Notice of rights.

NICE guidance is prepared for the National Health Service in England. All NICE guidance is subject to regular review and may be updated or withdrawn. NICE accepts no responsibility for the use of its content in this product/publication. 

Published date: 29 July 2021.