Characterization of Thrombosis After Vaccination: Analysis of The United
States Vaccine Adverse Event Reporting System
Abstract
Abstract: Background: Vaccines are considered one of the milestones of
modern medicine that promoted health and curbed morbidity and mortality.
However, with the rapid development and approval of different vaccines,
various thrombotic events have been reported. Yet, a comprehensive
analysis of vaccine-associated stroke and other thrombotic events is not
well-characterized. Methods: We utilized the vaccine adverse event
reporting system (VAERS) database from 1990-2021 to examine the
association between vaccines and thrombotic events. We analyzed the data
by sex and age, and vaccine type, and COVID-19 vaccine manufacturer.
Disproportionality signal analysis was conducted by measuring reporting
odds ratio (ROR) with a 95% confidence interval (CI). Results: Out of
over 1.3 million adverse events reported in VAERS, more than 6000 were
strokes between 1990-2021. Most strokes (70%) COVID-19 vaccines
accounted for over 80% of all vaccine-related strokes with ROR (CI
95%) of 13.3 (CI 12.4-14.3, p<0.0001). Among COVID-19
vaccines, Pfizer/Biotech was associated with 46%, Moderna with 40%,
and Janssen with 12% of strokes. Finally, our data revealed that
prothrombic diseases of various vascular territories were reported the
most among patients who have received COVID-19 vaccines with ROR (CI
95%) of 19.32 (CI 18.17-20.54; p <0.0001). Among these
thrombotic events myocardial infarction, pulmonary embolism, and deep
vein thrombosis were the most predominant. Conclusion: Our data suggest
a link between COVID-19 vaccines and thrombotic events, especially
strokes. This retrospective study highlights the urgent need for further
longitudinal studies to examine the safety of vaccines in patients with
high risk for thrombosis.