Abstract Number: PB1229
Meeting: ISTH 2022 Congress
Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » Platelet Function Disorders, Acquired
Background: During the first quarter of 2021, several European countries suspended the use of the Oxford–AstraZeneca vaccine amid reports of blood clot events and the death of a vaccinated person. This was followed by several reports of fatalities related to pulmonary embolism and other thrombotic events including thrombocytopenia which has been referred to as vaccine-induced immune thrombotic thrombocytopenia (VITT).
Aims: This study investigated the occurrence of thrombotic adverse events and their clinical outcomes of the three approved and most used COVID-19 vaccines namely Moderna, Pfizer and Oxford-AstraZeneca, using one of the largest spontaneous adverse events databases, namely EudraVigilance.
Methods: A retrospective descriptive analysis was conducted of spontaneous reports for Moderna, Pfizer and Oxford-AstraZeneca COVID-19 vaccines submitted to the EudraVigilance database in the period from 17 February to 14 June 2021.
Results: There were 729,496 adverse events for the three vaccines, of which 3,420 were thrombotic, mainly Oxford-AstraZeneca (n=1,988, 58·1%) followed by Pfizer (n=1,096, 32·0%) and Moderna (n=336, 9·8%). As serious adverse events, there were 705 reports of pulmonary embolism for the three vaccines, of which 130 reports (18·4%) were for Moderna, 226 reports (32·1%) for Pfizer and 349 (49·5%) for Oxford-AstraZeneca vaccines. The occurrence of pulmonary embolism is significantly associated with a fatal outcome (P= < 0·001). Sixty-three fatalities were recorded (63/3420, 1.8%), of which Moderna (n=6), Pfizer (n=25) and Oxford-AstraZeneca (n=32).
Conclusion(s): Thrombotic adverse events reported for the three vaccines remains extremely rare with multiple causative factors reported elsewhere as precipitating these events. Practicing vigilance and proper clinical management for the affected vaccines, as well as continuing to report adverse events, are essential. More than 4·89 billion doses of different COVID-19 vaccines have been administered across the globe. On the basis of scientific evidence showing that benefit outweighs risk, people continue to be urged to accept the vaccination when offered.
To cite this abstract in AMA style:
Tobaiqy M, MacLure K, Elkout H, Stewart D. Frequency of reported thrombotic adverse events and clinical outcomes associated with three COVID-19 vaccines [abstract]. https://abstracts.isth.org/abstract/frequency-of-reported-thrombotic-adverse-events-and-clinical-outcomes-associated-with-three-covid-19-vaccines/. Accessed March 21, 2024.« Back to ISTH 2022 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/frequency-of-reported-thrombotic-adverse-events-and-clinical-outcomes-associated-with-three-covid-19-vaccines/