Addressing the Elephant in the Room: Intravenous Injection of Coronavirus Disease 2019 mRNA

To the Editor—We read with great interest the article by Li et al who found that inadvertent intravenous (IV) injections of coronavirus disease 2019 (COVID-19) messenger RNA (mRNA) vaccines may cause acute myopericarditis in a murine model [1]. Although pertinent, we suggest that their findings be interpreted in the context of certain limitations and weighed against the broader context. Safety monitoring of the millions of doses of COVID-19 mRNA vaccines administered worldwide has found a generally low incidence of myocarditis among vaccine recipients, at 2 to 4 cases per 100 000 persons [2, 3]. Younger males appear to be at the highest risk of post-vaccination myocarditis [3]. In the present in vivo study, only the IV group showed histopathological changes of myopericarditis, not the group that received the intramuscular BNT162b2 mRNA COVID-19 vaccine. However, it is important to note that the authors administered...