Letter to the Editor: Long-Term Prognosis of Patients With Myocarditis Attributed to COVID-19 mRNA Vaccination, SARS-CoV-2 Infection, or Conventional Etiologies

"Semenzato et al. incorrectly concluded that patients who develop myocarditis following an mRNA COVID-19 vaccination experience fewer cardiovascular complications at 18 months compared to those with alleged myocarditis following a COVID-19 infection or an unusually large series of those with 'conventional' myocarditis allegedly not related to the infection or the vaccine. The study methodology raises numerous concerns...

The conclusions made by Semenzato et al. are not consistent with the literature. Watanabe and Hama found that the myocarditis mortality rate ratio (MMRR) was significantly higher in the COVID-19 vaccinated population compared to the general population during the three years preceding the COVID-19 pandemic, with a pronounced increase among young adults (MMRR: 7.80 for individuals in their 30s). The OpenSAFELY study found that myocarditis occurred only among COVID-19 vaccinated children and not SARS-CoV-2 infected children, with a sample size of over 1 million participants. Both mRNA and vaccine-derived Spike protein with inflammation have been found in the human heart in those who died after COVID-19 vaccination and in those with vaccine-induced myocarditis, respectively (Figure 1). Whereas autopsies of individuals who died from SARS-CoV-2 infection indicate that cardiac infection with the virus is not associated with myocarditis.

In conclusion, the study by Semenzato et al. is misleading. SARS-CoV-2 infection does not cause serious myocarditis, whereas COVID-19 vaccination is well recognized to cause symptomatic and fatal myocarditis."