The early impact of COVID-19 vaccines on major events in pulmonary, cardiac, and thromboembolic disease: a nationwide retrospective cohort study

This study, involving a nationwide Korean cohort, used health insurance data to investigate potential COVID-19 vaccine-related major outcomes, including pulmonary, cardiac, and thromboembolic diseases. This retrospective cohort study involved data from 2,017,884 vaccinated (at least two doses) individuals and 334,583 unvaccinated individuals. The incidences of major events of interest were compared between the vaccinated and the unvaccinated groups at 1 week to 3 months after vaccination. 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 hyperlipidemia 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. 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.