key: cord-0953860-h9spow3i
authors: Al-Samkari, Hanny; Leaf, Rebecca Karp; Goodarzi, Katayoon
title: Transient Thrombocytopenia With Glycoprotein-Specific Platelet Autoantibodies After Ad26.COV2.S Vaccination: A Case Report
date: 2021-09-14
journal: Ann Intern Med
DOI: 10.7326/l21-0427
sha: 9ac62ebd1802047cc16f7f31a4da8caca3aee130
doc_id: 953860
cord_uid: h9spow3i

nan

≥0.094), and 0.267 for anti-glycoprotein Ia/IIa (threshold, ≥0.108). The optical density positivity thresholds for each glycoprotein in this assay are set to twice the normal calibrator values (which are averaged from antibody-negative plasma samples from healthy donors).

The patient's platelet count was monitored closely and showed stability and rapid recovery without intervention as follows: at 43 days, 56 Â 10 9 cells/L; at 44 days, 67 Â 10 9 cells/L; at 45 days, 76 Â 10 9 cells/L; at 48 days, 143 Â 10 9 cells/L; and at 51 days, 248 Â 10 9 cells/L. Platelet autoantibody testing was repeated 3 weeks after platelet count normalization; results for all 3 platelet glycoproteins were negative.

Discussion: Platelet autoantibody testing is not routinely recommended in patients with suspected immune thrombocytopenia because of its modest sensitivity (about 50%) (5). However, when glycoprotein-specific antibody testing is done in adherence with expert guidelines, specificity is 90% to 95% (4, 5) . Although many vaccines are associated with thrombocytopenia, the occurrence of potentially fatal TTS may be uniquely associated with adenoviral vector vaccines against SARS-CoV-2. Therefore, characterizing the natural history of alternative causes of new-onset acute thrombocytopenia in recipients of these vaccines is of paramount importance. In this case, the patient had an initial presentation that was concerning for possible TTS, but on further evaluation, she was found to have transient immunologic thrombocytopenia with detected (and similarly transient) direct glycoprotein-specific platelet autoantibodies, suggesting that vaccination with Ad26.COV2.S may provoke transient production of antibodies targeted against, or capable of cross-reactivity with, platelet glycoproteins in certain individuals. If antiviral spike protein antibodies cross-reactive with platelet glycoproteins resulted in this clinical presentation, thrombocytopenia due to this mechanism could occur with other SARS-CoV-2 vaccines. The potential development of platelet autoantibodies or antiviral antibodies capable of crossreactivity with platelet glycoproteins after vaccination against SARS-CoV-2 is a phenomenon worthy of further study.

Thrombosis and thrombocytopenia after ChAdOx1 nCoV-19 vaccination

This article was published at Annals.org on 14

Thrombocytopenia following Pfizer and Moderna SARS-CoV-2 vaccination

A case of autoimmune hemolytic anemia following COVID-19 messenger ribonucleic acid vaccination

Platelet Immunology Scientific Subcommittee of the ISTH. Recommendations for the implementation of platelet autoantibody testing in clinical trials of immune thrombocytopenia

The sensitivity and specificity of platelet autoantibody testing in immune thrombocytopenia: a systematic review and metaanalysis of a diagnostic test