Background/aims: Although COVID-19 vaccines reduce COVID-19 severity, various safety concerns have emerged. This study, involving a population-based cohort, used health insurance data to investigate potential vaccine-related major outcomes, including cardiac, pulmonary, and thromboembolic diseases.
Methods: This retrospective cohort study involved data from 2,017,884 vaccinated (at least two doses) individuals and 334,583 unvaccinated individuals. The incidences of myocarditis, myocardial infarction, atrial fibrillation, interstitial lung disease, pulmonary thromboembolism, deep vein thrombosis, and cerebrovascular disease were compared between the vaccinated and the unvaccinated groups at 1 week to 3 months after vaccination.
Results: The study population had a mean age of 54 years (male: 44.6%). Among the vaccinated, 57.7% received the mRNA vaccine only, whereas 35.5% received the adenoviral vector vaccine alone. Multivariate logistic analysis revealed that vaccination was significantly associated with the early development of myocarditis. The mRNA vaccine, a younger age, and retrohyperlipidemia were independent indicators of poor myocarditis prognosis after vaccination. However, the incidence of myocardial infarction at 1-2 weeks post-vaccination, as well as pulmonary thromboembolism and cerebrovascular disease (both at 3 months post-vaccination), were significantly lower in the vaccinated group when compared with the unvaccinated one. However, there was no significant association between vaccination and interstitial lung disease, atrial fibrillation, or deep vein thrombosis.
Conclusion: The younger male population (age: < 45 years) should be cautious about receiving the COVID-19 mRNA vaccine and should be closely monitored for myocarditis after vaccination. Vaccination was associated with short-term protection against venous and arterial thrombotic events, as well as hemorrhagic events.
Keywords: COVID-19 vaccines; Cerebrovascular disorders; Myocardial infarction; Myocarditis; Pulmonary embolism.