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    Poster Networking

    COVID

    Poster Networking Session

    PB0058 - The risk of developing thrombotic events in individuals with antithrombin deficiency undergoing Covid vaccination: a family cohort study.

    Sunday, June 25, 2023
    18:30 – 19:30 ET
    Room: Exhibition

      Co-Author(s)

    • DT

      Daniela Tormene

      MD, PhD
      University of Padova
      Padova, Veneto, Italy

      • Co-Author(s)

    • EB

      Elena Bicego

      MD
      Padua University
      Padova, Veneto, Italy

    • NP

      Nicola Perin

      Resident in internal MEedicine
      Department of Medicine, University of Padova, Italy
      Padova, Veneto, Italy

    • Elena Campello, MD, PhD (she/her/hers)

      Assistant Professor
      Department of Medicine, University of Padova, Italy
      Padova, Veneto, Italy

    • MS

      Marta Sartori

      MD
      Padua University
      vicenza, Veneto, Italy

      • Presenting Author(s)

    • Chiara Simion, MD

      Resident in Geriatrics
      Department of Medicine, University of Padova, Italy
      Padova, Veneto, Italy

      • Co-Author(s)

    • Paolo Simioni, MD, PhD (he/him/his)

      Full Professor
      Department of Medicine, Thrombotic and Haemorrhagic Diseases Unit, University of Padua Medical School, Padua (Italy)
      Padua, Veneto, Italy

    Background: After SARS-CoV-2 vaccination campaign initiation, rare, unusual, and severe thrombotic events have been reported in connection with some of the SARS-CoV-2 vaccines, and have caused a lot of worry and a severe confusion within the population and the medical community.

    Aims: Antithrombin deficiency is recognized as the most severe form of inherited thrombophilia.

    Methods: We estimated the absolute risk of thrombosis within 30 days of each single dose of 3 SARS-CoV-2 vaccinations [ ChAdOx1-S (AstraZeneca) , COVID-19 Vaccine Moderna mRNA -1273 (Spikevax), Pfizer mRNABNT162b2 (Comirnaty)] in carriers of antithrombin deficiency, compared with non carriers.

    Results: Out of 141 subjects, 81 were carriers of antithrombin deficiency and 60were not. In the group of defect carriers 68 received three vaccine doses, 6 two doses and 2 received 1 dose; 3 carriers refused vaccination. In the non-carrier group 55 received three vaccine doses, and one two doses; 4 non-carriers refused vaccination. A total of 220 (172 Comirnaty, 32 Spikevax, 16 ChAdOx1-S) and 167 (109 Comirnaty,48 Spikevax, 10 ChAdOx1-S) vaccine doses were administered in carriers and non-carriers, respectively. Thirty-five carriers of the defect were taking anticoagulant therapy for previous thrombotic events.
    Only one thrombotic event occurred in a 44-year-old woman with the defect two weeks after receiving the second dose of the vaccine. The relative risk was of 0.75 (95% CI 0.05 to 11.8); even when anticoagulated patients were excluded the relative risk was of 1.3 (95% CI 0.08 to 20). Six carriers developed covid disease (one before vaccination, one after the first dose, 2 after the second, 2 after the third) versus two in the non-carrier group (after the third dose): RR 2.14 (95% CI 0.5 to 10.2).

    Conclusion(s): The data of our study show that even in patients genetically predisposed to an increased thrombotic risk, vaccination against Covid does not seem to increase this risk.