Abstract Number: VPB0119
Meeting: ISTH 2022 Congress
Theme: COVID and Coagulation » COVID and Coagulation, Clinical
Background: With widespread COVID-19 immunization efforts, reports of vaccine-induced thrombocytopenia and thrombosis (VITT) have emerged, particularly in association with adenoviral vector-based vaccines (ChAdOx1 nCoV-19 and Ad26.COV2.S). The incidence of VITT is considered to be extremely low, with the benefits of vaccination strongly outweighing associated risks. Despite the favorable safety profile of COVID-19 vaccines, VITT has garnered the attention of and likely contributes to vaccine hesitancy among a persistently unvaccinated portion of the United States population.
Aims: We sought to characterize thrombotic events following COVID-19 vaccination in a large clinical enterprise where mRNA-based vaccines were mostly administered.
Methods: With institutional approval, medical records of 779,602 patients vaccinated against COVID-19 (2 mRNA-based vaccines: 61.2% BNT162b2, 36% mRNA-1273, and adenovirus-based Ad26.COV2.S, 2.7%) from 12/4/2020-6/6/2021 at Cleveland Clinic Enterprise locations in Ohio and Florida were queried. A baseline complete blood count was available for 223,345 patients, of which 663 (0.3%) demonstrated thrombocytopenia—defined as ≥50% platelet decline 4-28 days post-vaccination—and were subject to chart review. Thrombotic events including deep vein thrombosis, pulmonary embolism, stroke/transient ischemic attack, myocardial infarction, cerebral venous sinus thrombosis, and splanchnic thrombosis were assessed. Thrombotic risk factors including medications, viruses, and malignancy, as well as platelet factor 4 antibody assays were recorded.
Results: Of 76 patients with thrombosis, 63 (82.9%) demonstrated clear etiologies. Thirty (39.5%) had malignancies (24 treated with chemotherapy associated with thrombosis risk). Seven (9.2%) were considered hypercoagulable, six (7.9%) had catheter-related thrombosis, five (6.6%) had recent surgery, five (6.6%) had reduced mobility, five (6.6%) had cardiovascular risk factors, three (3.9%) had diagnosed/suspected immune thrombocytopenia, and two (2.6%) were septic. Of three patients with unprovoked thrombosis, one had findings concerning for VITT (Figure 1).
Conclusion(s): 76/223,345 (0.03%) patients demonstrated thrombosis following COVID-19 vaccination, with one (0.0004%) case concerning for VITT. In a large clinical enterprise, VITT is exquisitely rare.
Image
Figure 1. Patients vaccinated against COVID-19 with at least 50% decrease in platelet count from baseline in the following 28 days.
To cite this abstract in AMA style:
Greene B, Patterson W, Tefera L, Bena J, Milinovich A, Mehta N, Chung M, Cameron S. Evaluation of thrombotic outcomes in patients in a large clinical enterprise following COVID-19 vaccination [abstract]. https://abstracts.isth.org/abstract/evaluation-of-thrombotic-outcomes-in-patients-in-a-large-clinical-enterprise-following-covid-19-vaccination/. Accessed October 1, 2023.« Back to ISTH 2022 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/evaluation-of-thrombotic-outcomes-in-patients-in-a-large-clinical-enterprise-following-covid-19-vaccination/