A common question from followers concerns the differential safety profiles of the COVID-19 vaccines. A large-scale study from Korea has revealed some important differences, unfortunately for the majority of vaccine-takers who opted for mRNA products from Pfizer and Moderna.
Yun et al, used the South Korea NHIS COVID-19 database, covering the period from October 2018 to March 2022. This comprehensive database comprises medical claims of 10,663,738 individuals, representing approximately 24% of the South Korean population who received one or more vaccines from February 2021 to March 2022 (n=3,350,855). The variables of interest were the type of vaccine (mRNA/Others) and the COVID-19 status (yes/no). The mRNA vaccines consisted of BNT162b2 (Pfizer/bioNTech) and mRNA-1273 (Moderna). Other vaccines included AZD1222 (AstraZeneca), JNJ 78436735 (Janssen), and NVX-CoV2373 (Novavax). The primary outcome variable in this study was the occurrence of acute heart diseases. The acute heart diseases included acute cardiac injury (ICD-10: I21), acute myocarditis (ICD-10: I40), acute pericarditis, unspecified (ICD-10: I309), cardiac arrest, unspecified (ICD-10: I469), and cardiac arrhythmia, unspecified (ICD-10: I499). They extracted the date of the initial diagnosis of acute heart diseases and defined occurrences within 21 days after the first vaccination date as potential AEs related to vaccination. The results showed the short term cardiac risks were much higher for mRNA products.
Yun C, Lee Y, Heo SJ, Kim N, Jung I. The impact of COVID-19 status and vaccine type following the first dose on acute heart disease: A nationwide retrospective cohort study in South Korea. Epidemiol Infect. 2024 Oct 24;152:e134. doi: 10.1017/S0950268824001213. PMID: 39444354.
Of note, important covariates that increased the cardiac risk with mRNA were: contracting COVID-19 at any time, younger age groups, and higher comorbidities or baseline medical problems.
It should come to attention by oversight bodies that public health agencies never studied comparative safety and investigations into why the agencies preferentially promoted mRNA vaccines despite their higher risk of cardiovascular events.