A recent study by South Korean researchers has indicated that individuals who received a single dose of an mRNA-based COVID-19 vaccine faced a higher risk of acute heart disease compared to those who received a non-mRNA vaccine.
Published on October 24 in Epidemiology and Infection, the peer-reviewed study highlights an increased risk among individuals aged 10 to 59, with reduced impact noted among those 60 and older.
The research team analyzed data from South Korea’s National Health Insurance Service (NHIS) on over 3.3 million vaccinated individuals from February 2021 to March 2022.
During this period, five COVID-19 vaccines were administered in South Korea: two mRNA vaccines (Pfizer-BioNTech and Moderna) and three non-mRNA vaccines (AstraZeneca, Janssen, and Novavax).
The study aimed to determine whether individuals who received a first dose of an mRNA vaccine had a greater likelihood of experiencing acute cardiac events, including cardiac injury, myocarditis, pericarditis, cardiac arrest, and arrhythmia, within the first 21 days post-vaccination.
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Key findings revealed that recipients of mRNA vaccines had a notably higher incidence of these cardiac events than those who received non-mRNA vaccines.
Additionally, contracting COVID-19 within the same 21-day period was also associated with a significantly increased heart disease risk, though this was independent of the vaccine type. Younger recipients of mRNA vaccines, particularly those under 60, showed a higher risk than older recipients, suggesting an age-related variance in vaccine safety profiles.
Dr. Peter McCullough, who discussed the study on his Substack, expressed concern about public health agencies’ prioritization of mRNA vaccines without more comprehensive comparative safety data.
He advocated for further investigations into why agencies emphasized mRNA vaccines despite the potential for cardiovascular side effects.
Karl Jablonowski, Ph.D., a senior researcher at Children’s Health Defense, echoed this sentiment. He described the findings as “compelling,” noting that the biological plausibility of mRNA vaccines increasing heart disease risk goes beyond the established risks of myocarditis and pericarditis. He pointed to the need for further research using population-level data to better capture potential risks.
The authors acknowledged limitations in their study, which only tracked cardiac adverse events within 21 days of the first vaccine dose, driven by data constraints within the NHIS COVID-19 database.
They noted that a more extended analysis, especially post-second dose, could provide a more comprehensive understanding of the risk.
Other studies have shown that myocarditis and pericarditis risks are more pronounced after the second mRNA dose, suggesting further research could yield additional insights.
Jablonowski cautioned about potential temporal bias, as not all vaccine types were simultaneously available, potentially affecting the risk outcomes.
He suggested that a timeline plot of vaccine type, COVID-19 incidence, and heart disease events could help identify any such temporal influence on the results, underscoring the complexity of interpreting population-based health data.
This study underscores the importance of nuanced vaccine risk assessment, particularly for age groups facing heightened vulnerability, and it calls for ongoing vigilance in vaccine safety monitoring.