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    COVID

    Publication Only

    PO04 - SARS-CoV-2 vaccinations and risk of Venous Thrombosis – Case control study

    Wednesday, June 28, 2023
    13:00 – 14:00 ET
    Room: 10

      Presenting Author(s)

    • Willian J. van Dijk, MD (he/him/his)

      PhD student
      Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, the Netherlands
      Vlaardingen, Zuid-Holland, Netherlands

      • Co-Author(s)

    • AK

      Agnes Kant

      Director
      Netherlands Pharmacovigilance Centre Lareb
      Doesburg, Gelderland, Netherlands

    • FR

      Frits R. R. Rosendaal

      Professor
      Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands
      Leiden, Zuid-Holland, Netherlands

    • Astrid van Hylckama Vlieg, PhD

      Associate Professor
      Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands
      Leiden, Zuid-Holland, Netherlands

    Background: Conflicting results have been reported regarding the magnitude of the risk of venous thromboembolism (VTE) after SARS-CoV-2 vaccination.

    Aims: To determine the risk of VTE after SARS-CoV-2 vaccination and to determine whether there are subgroups of individuals who are particularly at increased risk of VTE after vaccination.

    Methods: Patients who had a first VTE in 2021 were selected from the files of several large hospitals in the Netherlands using ICD coding. Controls were included from a population-based longitudinal cohort of 7000 random selected Dutch citizens, without a thrombotic event in 2021. Participants were over 18 years old, able to understand Dutch or English, and were legally competent. Informed consent was obtained from all participants. The study was approved by local medical ethics committee and is funded by the Dutch Ministry of Health.
    A questionnaire was sent to both the patients and the controls. The questionnaire contained questions regarding history of VTE, details regarding vaccination status (date, type of vaccine), and other risk factors for VTE. After matching on calendar date (1:3) odds ratios (OR; adjusted for age and sex) will be calculated to assess the association between SARS-CoV-2 vaccination and the risk of VTE. The risk of VTE will be calculated separately for different SARS-CoV-2 vaccines. Furthermore, subgroup analysis will be performed to identify potential high risk groups for developing VTE after SARS-CoV-2 vaccination. A risk window of 28 days was applied but as detailed information is available, varying risk windows can be considered.

    Results: Data collection is currently ongoing and will be complete at the time of the conference.

    Conclusion(s): The results will give insight into the risk of VTE after SARS-CoV-2 vaccination and specifically whether there is a difference between types of vaccination. Furthermore, results will show whether preventive measures may be targeted to specific high-risk populations.