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Assessing Clinically Meaningful Hypercoagulability after COVID-19 Vaccination: A Longitudinal Study
Elena Campello1, Cristiana Bulato1, Chiara Simion1
1General Internal Medicine and Thrombotic and Hemorrhagic Diseases Unit, Department of Medicine, Padova University Hospital, Veneto, Italy.
Thrombosis and Haemostasis
|March 7, 2022
Summary
COVID-19 vaccination did not cause clinically significant hypercoagulability. Thrombin generation slightly increased after the first dose of ChAdOx1 vaccine and the second dose of either vaccine, but resolved quickly without adverse events.
Area of Science:
- Hematology
- Immunology
- Vaccinology
Background:
- Concerns regarding prothrombotic risk factors following COVID-19 vaccination prompted investigation.
- Longitudinal evaluation of coagulation profiles is crucial for vaccine safety assessment.
Purpose of the Study:
- To longitudinally assess coagulation profiles in healthy individuals post-COVID-19 vaccination.
- To determine if COVID-19 vaccines (ChAdOx1 and BNT162b2) induce hypercoagulability.
Main Methods:
- Enrolled 122 healthy volunteers receiving ChAdOx1 or BNT162b2 vaccines.
- Collected venous blood samples at baseline, 3±2 days (T1), and 10±2 days (T2) post-vaccination.
- Assessed coagulation via platelet count, thromboelastometry, aggregometry, thrombin generation, and anti-PF4/heparin antibodies.
Main Results:
- A transient increase in thrombin generation (ETP) was observed after the first ChAdOx1 dose (T1).
- The second vaccine dose (either type) increased thrombin peak and ETP.
- No clinically meaningful hypercoagulability, thrombotic, or hemorrhagic events were detected.
Conclusions:
- COVID-19 vaccination with ChAdOx1 or BNT162b2 does not lead to clinically significant hypercoagulability.
- Transient increases in thrombin generation may occur, particularly after the second vaccine dose.
- Findings support the safety of COVID-19 vaccines regarding thrombotic risk.
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