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Frequency of positive anti-PF4/polyanion antibody tests after COVID-19 vaccination with ChAdOx1 nCoV-19 and BNT162b2.
Thiele, Thomas; Ulm, Lena; Holtfreter, Silva; Schönborn, Linda; Kuhn, Sven Olaf; Scheer, Christian; Warkentin, Theodore E; Bröker, Barbara M; Becker, Karsten; Aurich, Konstanze; Selleng, Kathleen; Hübner, Nils-Olaf; Greinacher, Andreas.
  • Thiele T; Department of Transfusion Medicine, Institute of Immunology and Transfusion Medicine.
  • Ulm L; Friedrich-Loeffler Institute of Medical Microbiology.
  • Holtfreter S; Department of Immunology, Institute of Immunology and Transfusion Medicine, and.
  • Schönborn L; Department of Transfusion Medicine, Institute of Immunology and Transfusion Medicine.
  • Kuhn SO; Department of Anaesthesiology, University Medicine Greifswald, Greifswald, Germany.
  • Scheer C; Department of Anaesthesiology, University Medicine Greifswald, Greifswald, Germany.
  • Warkentin TE; Department of Pathology and Molecular Medicine and.
  • Bröker BM; Department of Medicine, McMaster University, Hamilton, ON, Canada; and.
  • Becker K; Department of Immunology, Institute of Immunology and Transfusion Medicine, and.
  • Aurich K; Friedrich-Loeffler Institute of Medical Microbiology.
  • Selleng K; Department of Transfusion Medicine, Institute of Immunology and Transfusion Medicine.
  • Hübner NO; Department of Transfusion Medicine, Institute of Immunology and Transfusion Medicine.
  • Greinacher A; Central Unit for Infection Prevention and Control, University Medicine Greifswald, Greifswald, Germany.
Blood ; 138(4): 299-303, 2021 07 29.
Article in English | MEDLINE | ID: covidwho-1228983
ABSTRACT
Vaccination using the adenoviral vector COVID-19 vaccine ChAdOx1 nCoV-19 (AstraZeneca) has been associated with rare vaccine-induced immune thrombotic thrombocytopenia (VITT). Affected patients test strongly positive in platelet factor 4 (PF4)/polyanion enzyme immunoassays (EIAs), and serum-induced platelet activation is maximal in the presence of PF4. We determined the frequency of anti-PF4/polyanion antibodies in healthy vaccinees and assessed whether PF4/polyanion EIA+ sera exhibit platelet-activating properties after vaccination with ChAdOx1 nCoV-19 (n = 138) or BNT162b2 (BioNTech/Pfizer; n = 143). In total, 19 of 281 participants tested positive for anti-PF4/polyanion antibodies postvaccination (All 6.8% [95% confidence interval (CI), 4.4-10.3]; BNT162b2 5.6% [95% CI, 2.9-10.7]; ChAdOx1 nCoV-19 8.0% [95% CI, 4.5% to 13.7%]). Optical densities were mostly low (between 0.5 and 1.0 units; reference range, <0.50), and none of the PF4/polyanion EIA+ samples induced platelet activation in the presence of PF4. We conclude that positive PF4/polyanion EIAs can occur after severe acute respiratory syndrome coronavirus 2 vaccination with both messenger RNA- and adenoviral vector-based vaccines, but many of these antibodies likely have minor (if any) clinical relevance. Accordingly, low-titer positive PF4/polyanion EIA results should be interpreted with caution when screening asymptomatic individuals after vaccination against COVID-19. Pathogenic platelet-activating antibodies that cause VITT do not occur commonly following vaccination.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: Purpura, Thrombotic Thrombocytopenic / Autoantibodies / Platelet Factor 4 / Vaccination / Polyelectrolytes / COVID-19 Vaccines / COVID-19 Type of study: Prognostic study Topics: Vaccines Limits: Adult / Female / Humans / Male / Middle aged Language: English Journal: Blood Year: 2021 Document Type: Article

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Full text: Available Collection: International databases Database: MEDLINE Main subject: Purpura, Thrombotic Thrombocytopenic / Autoantibodies / Platelet Factor 4 / Vaccination / Polyelectrolytes / COVID-19 Vaccines / COVID-19 Type of study: Prognostic study Topics: Vaccines Limits: Adult / Female / Humans / Male / Middle aged Language: English Journal: Blood Year: 2021 Document Type: Article