Most anti-PF4 antibodies in vaccine-induced immune thrombotic thrombocytopenia are transient.

Abstract

Vaccine-induced thrombotic thrombocytopenia (VITT) is triggered by vaccination against COVID-19 with adenovirus vector vaccines (ChAdOx1 nCoV-19; Ad26.COV2-S). In this observational study, we followed VITT patients for changes in their reactivity of platelet-activating antiplatelet factor 4 (PF4) immunoglobulin G (IgG) antibodies by an anti-PF4/heparin IgG enzyme immunoassay (EIA) and a functional test for PF4-dependent, platelet-activating antibodies, and new thrombotic complications. Sixty-five VITT patients (41 females; median, 51 years; range, 18-80 years) were followed for a median of 25 weeks (range, 3-36 weeks). In 48/65 patients (73.8%; CI, 62.0% to 83.0%) the functional assay became negative. The median time to negative functional test result was 15.5 weeks (range, 5-28 weeks). In parallel, EIA optical density (OD) values decreased from median 3.12 to 1.52 (P < .0001), but seroreversion to a negative result was seen in only 14 (21.5%) patients. Five (7.5%) patients showed persistent platelet-activating antibodies and high EIA ODs for >11 weeks. None of the 29 VITT patients who received a second vaccination dose with an mRNA COVID-19 vaccine developed new thromboses or relevant increase in anti-PF4/heparin IgG EIA OD, regardless of whether PF4-dependent platelet-activating antibodies were still present. PF4-dependent platelet-activating antibodies are transient in most patients with VITT. VITT patients can safely receive a second COVID-19 mRNA-vaccine shot.

• Authors: Linda Schönborn, Thomas Thiele, Lars Kaderali, Albrecht Günther, Till Hoffmann, Sabrina Edigna Seck, Kathleen Selleng, Andreas Greinacher
• Journal: Blood (Blood) Vol. 139 Issue 12 Pg. 1903-1907 (03 24 2022) ISSN: 1528-0020 [Electronic] United States
• PMID: 35113987 (Publication Type: Journal Article, Observational Study, Research Support, Non-U.S. Gov't)
• Copyright: © 2022 by The American Society of Hematology.

Chemical References

• COVID-19 Vaccines
• Immunoglobulin G
• Vaccines
• Platelet Factor 4
• Heparin
• ChAdOx1 nCoV-19

Topics

• COVID-19 (prevention & control)
• COVID-19 Vaccines (adverse effects)
• ChAdOx1 nCoV-19
• Female
• Heparin (adverse effects)
• Humans
• Immunoglobulin G
• Platelet Factor 4
• Thrombocytopenia (chemically induced)
• Thrombosis
• Vaccines (adverse effects)