Overview

Thrombotic Thrombocytopenia Syndrome (TTS) has emerged as a new adverse event following immunization in individuals vaccinated with COVID-19 non-replicant adenovirus vector-based vaccines (AstraZeneca COVID-19 ChAdOx-1 vaccine and Johnson & Johnson (J&J) Janssen COVID-19 Ad26.COV2-S vaccine). TTS is a serious and life-threatening adverse event. WHO has issued this interim emergency guidance to increase awareness about TTS in the context of COVID-19 vaccination and help healthcare providers in the assessment and management of potential TTS cases. Knowledge about TTS following vaccination with a COVID-19 adenovirus vector-based vaccine is rapidly evolving. WHO will continue to monitor the situation closely for any changes that may affect this interim guidance and will update the guidance as needed.

Contents

• Acknowledgements
• Abbreviations and acronyms
• Executive summary
• Chapter 1. Introduction
  • 1.1. Background
  • 1.2. Rationale for the updated guidance
  • 1.3. Aim of the updated guidance
• Chapter 2. Guideline development process and methods
  • 2.1. Guideline Development Group
  • 2.2. Methodology for evidence to recommendations in the interim guidance – July 2021
  • 2.3. Methodology for evidence to recommendations in the updated guidance – June 2022
  • 2.4. Timeline for the updated guidance
  • 2.5. Literature search
  • 2.6. Quality assessment
  • 2.7. Summary of findings
  • 2.8. External review
  • 2.8. Limitations
  • 2.9. Evidence to decision-making for updated treatment guidance
  • 2.9. Formulation of recommendation in the updated guidance based on evidence presented
• Chapter 3. Treatment recommendations and rationale
  • 1. All patients who present with TTS following vaccination with a COVID-19 vaccine should receive anti-coagulation treatment (strong, very low certainty)
  • 2. Heparin may be used for anti-coagulation in patients with TTS following vaccination with a COVID-19 vaccine (conditional, very low certainty)
  • 3. IVIGs should be used for treating individuals with TTS following vaccination with a COVID-19 vaccine (strong, very low certainty)
  • 4. Platelet transfusion should not be used for treatment of patients with TTS following vaccination with a COVID-19 vaccine, except in emergency situations where surgery is strongly indicated, thrombocytopenia is severe and platelet transfusion is required (strong, very low certainty)
  • 5. KEY CONSIDERATION: The GDG did not provide any recommendation on steroid treatment but noted the general use of steroids and the likelihood that steroids would usually be given in combination with other treatments
• References
• Annex 1. Contributors
• Annex 2. Search strategies for bibliographic databases: PubMed, WHO COVID-19 Database and Global Index Medicus
• Web Annex A. Background document
• Web Annex B. Treatment options for patients diagnosed with TTS following COVID-19 vaccination: Evidence-to-decision tables

Suggested citation:

Guidance for clinical case management of thrombosis with thrombocytopenia syndrome (TTS) following vaccination to prevent coronavirus disease (COVID-19). Geneva: World Health Organization; 2023. Licence: CC BY-NC-SA 3.0 IGO.

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This publication replaces the interim guidance published under WHO reference number WHO/2019-nCoV/TTS/2021.1.