24 in 1,000,000 affected by Myocarditis & covid jab

None of the US case series reports are population based,^1,2,4 and therefore, estimating rates of myocarditis following COVID-19 vaccination is problematic. However, based on data available to date, we can say that myocarditis occurring after COVID-19 immunization is rare. Kim et al¹ estimated that more than 560 000 persons in the 6 counties surrounding their tertiary care institution had received 2 doses of an mRNA-based COVID-19 vaccine by April 30, 2021; they detected 4 myocarditis cases by that date.¹ The Military Health System administered more than 2.8 million doses of mRNA-based vaccines through April 30, 2021, and detected 23 myocarditis cases.² Based on the military’s extensive experience with vaccinia-associated myocarditis,⁹ it is possible that the military system may be more likely to detect mild myocarditis cases than most civilian medical centers. Among the 436 000 male active-duty military who have received 2 mRNA vaccine doses, Montgomery et al² estimated that 0 to 8 cases of myocarditis might be expected based on US data on the background incidence rate of myocarditis, whereas they detected 19 myocarditis cases in that group.² The most comprehensive data about the risk of myocarditis following immunization with mRNA vaccines comes from Israel. The Israeli Ministry of Health recently posted data describing 121 myocarditis cases occurring within 30 days of a second dose of mRNA vaccine among 5 049 424 persons, suggesting a crude incidence rate of approximately 24 cases per million following a second dose in this subset of their vaccinated population.¹⁰

While more definitive data on the incidence of myocarditis following immunization with mRNA COVID-19 vaccines and associated risk will eventually be provided by large population-based vaccine adverse event monitoring systems, including the US Centers for Disease Control and Prevention Vaccine Safety Datalink,¹¹ several interim conclusions can be offered. Cardiac injury after SARS-CoV-2 infection occurs and may result in severe outcomes.⁸ Based on currently available data, myocarditis following immunization with current mRNA-based vaccines is rare. All possible myocarditis cases should be reported to the US Vaccine Adverse Events Reporting System to help better define the characteristics of this syndrome and its relationship to receipt of mRNA-based COVID-19 vaccines authorized for use in the US. At present, the benefits of immunization in preventing severe morbidity favors continued COVID-19 vaccination, particularly considering the increasing COVID-19 hospitalization rates among adolescents reported during spring 2021.¹² Many questions remain. What modifications to the vaccine schedule, if any, should be considered among persons with a history of possible or confirmed myocarditis after a first dose of COVID-19 vaccine? How should postvaccine myocarditis be managed, particularly given the apparently benign outcomes described thus far and the success of supportive or conservative management alone? How often should follow-up assessments, including repeated cardiac imaging, be performed in these patients, and how might follow-up assessments affect recommendations to avoid vigorous physical activity following the diagnosis of myocarditis? Do all likely cases of acute myocarditis that appear to be uncomplicated require cardiac magnetic resonance imaging for more definitive diagnosis? While the data needed to answer such questions are being collected, there is an opportunity for researchers with expertise in myocarditis to develop a comprehensive, national assessment of the natural history, pathogenesis, and treatment of acute myocarditis associated with receipt of mRNA-based COVID-19 vaccines.

Finally, the Centers for Disease Control and Prevention Advisory Committee on Immunization Practices held a public meeting from June 23 to 25, 2021. On June 23, the committee heard presentations about the epidemiology of myocarditis and pericarditis, an update on COVID-19 vaccine safety, including myocarditis following receipt of mRNA-based COVID-19 vaccines, and a benefit-risk assessment of COVID-19 mRNA vaccination programs in adolescents and young adults. Advisory Committee on Immunization Practices discussions and recommendations are summarized on the Centers for Disease Control and Prevention website.¹³