Pathologic Antibodies to Platelet Factor 4 after ChAdOx1 nCoV-19 Vaccination



Scully, Marie, Singh, Deepak, Lown, Robert, Poles, Anthony, Solomon, Tom ORCID: 0000-0001-7266-6547, Levi, Marcel, Goldblatt, David, Kotoucek, Pavel, Thomas, William and Lester, William
(2021) Pathologic Antibodies to Platelet Factor 4 after ChAdOx1 nCoV-19 Vaccination. NEW ENGLAND JOURNAL OF MEDICINE, 384 (23). pp. 2202-2211.

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Abstract

<h4>Background</h4>The mainstay of control of the coronavirus disease 2019 (Covid-19) pandemic is vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Within a year, several vaccines have been developed and millions of doses delivered. Reporting of adverse events is a critical postmarketing activity.<h4>Methods</h4>We report findings in 23 patients who presented with thrombosis and thrombocytopenia 6 to 24 days after receiving the first dose of the ChAdOx1 nCoV-19 vaccine (AstraZeneca). On the basis of their clinical and laboratory features, we identify a novel underlying mechanism and address the therapeutic implications.<h4>Results</h4>In the absence of previous prothrombotic medical conditions, 22 patients presented with acute thrombocytopenia and thrombosis, primarily cerebral venous thrombosis, and 1 patient presented with isolated thrombocytopenia and a hemorrhagic phenotype. All the patients had low or normal fibrinogen levels and elevated d-dimer levels at presentation. No evidence of thrombophilia or causative precipitants was identified. Testing for antibodies to platelet factor 4 (PF4) was positive in 22 patients (with 1 equivocal result) and negative in 1 patient. On the basis of the pathophysiological features observed in these patients, we recommend that treatment with platelet transfusions be avoided because of the risk of progression in thrombotic symptoms and that the administration of a nonheparin anticoagulant agent and intravenous immune globulin be considered for the first occurrence of these symptoms.<h4>Conclusions</h4>Vaccination against SARS-CoV-2 remains critical for control of the Covid-19 pandemic. A pathogenic PF4-dependent syndrome, unrelated to the use of heparin therapy, can occur after the administration of the ChAdOx1 nCoV-19 vaccine. Rapid identification of this rare syndrome is important because of the therapeutic implications.

Item Type: Article
Uncontrolled Keywords: Humans, Thrombosis, Thrombocytopenia, Heparin, Platelet Factor 4, Anticoagulants, Antibodies, Viral, Autoantibodies, Flow Cytometry, Algorithms, Adult, Aged, Middle Aged, Female, Male, COVID-19, COVID-19 Vaccines, ChAdOx1 nCoV-19
Divisions: Faculty of Health and Life Sciences
Faculty of Health and Life Sciences > Institute of Infection, Veterinary and Ecological Sciences
Depositing User: Symplectic Admin
Date Deposited: 07 Oct 2021 07:40
Last Modified: 17 Apr 2023 12:50
DOI: 10.1056/NEJMoa2105385
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3122213