Myocarditis Following Coronavirus Disease 2019 mRNA Vaccine: A Case Series and Incidence Rate Determination

Abstract

Background Myocarditis following coronavirus disease 2019 (COVID-19) mRNA vaccines (Pfizer-BioNTech and Moderna) has been increasingly reported. Incidence rates in the general population are lacking, with pericarditis rather than myocarditis diagnostic codes being used to estimate background rates. This comparison is critical for balancing the risk of vaccination with the risk of no vaccination. Methods A retrospective case series was performed using the Mayo Clinic COVID-19 Vaccine Registry. We measured the incidence rate ratio (IRR) for myocarditis temporally related to COVID-19 mRNA vaccination compared with myocarditis in a comparable population from 2016 through 2020. Clinical characteristics and outcomes of the affected patients were collected. A total of 21 individuals were identified, but ultimately 7 patients met the inclusion criteria for vaccine-associated myocarditis. Results The overall IRR of COVID-19–related myocarditis was 4.18 (95% confidence interval [CI], 1.63–8.98), which was entirely attributable to an increased IRR among adult males (IRR, 6.69; 95% CI, 2.35–15.52) compared with females (IRR 1.41; 95% CI, .03–8.45). All cases occurred within 2 weeks of a dose of the COVID-19 mRNA vaccine, with the majority occurring within 3 days (range, 1–13) following the second dose (6 of 7 patients, 86%). Overall, cases were mild, and all patients survived. Conclusions Myocarditis is a rare adverse event associated with COVID-19 mRNA vaccines. It occurs in adult males with significantly higher incidence than in the background population. Recurrence of myocarditis after a subsequent mRNA vaccine dose is not known at this time.

Use of analgesics/antipyretics in the management of symptoms associated with COVID-19 vaccination

“…An aspect that remains unknown is how effective analgesics/ antipyretics would be in preventing rare but serious adverse events such as myocarditis/pericarditis and thrombosis [61][62][63][64] . As inflammation, at least in part, contributes to these serious adverse events 65,66 , anti-inflammatory treatments should also reduce the risk of such rare events.…”

Epidemiology, clinical ramifications, and cellular pathogenesis of COVID-19 mRNA-vaccination-induced adverse cardiovascular outcomes: A state-of-the-heart review

“…Although the data is limited, studies have already been conducted to differentiate clinical presentation of MI from myocarditis post-COVID-19 vaccinations. In summary, those with post-vaccination MI presented at around 24 h post-vaccination, much earlier than myocarditis at 72 h [7] , [8] , [9] , [10] . More importantly, most developed MI symptoms after the first dose [9] , [10] .…”

“…Study cohort characteristics, comorbidities, clinical presentation, diagnostic evaluation, and outcome are all summarized. Case Series Myocarditis Following COVID-19 mRNA Vaccine: A Case Series and Incidence Rate Determination Acute myocardial infarction and myocarditis following COVID-19 vaccination Myocarditis and pericarditis in association with COVID-19 mRNA-vaccination: cases from a regional pharmacovigilance center Myocarditis Following Immunization With mRNA COVID-19 Vaccines in Members of the US Military Patients With Acute Myocarditis Following mRNA COVID-19 Vaccination Myocarditis and Pericarditis After Vaccination for COVID-19 Case Report Acute Myocarditis after COVID-19 vaccination: A case report Study Perez et al [7] Aye et al [9] Istampoulouoglou et al [24] Montgomery et al [25] Kim et al [26] Diaz et al [27] Study Schmitt et al [31] Characteristics Characteristics Cases, n 7 42 5 23 4 20 Case, n 1 Male, % 6 (86%) 38 (91%) 3 (60%) 23 (100%) 3 (75%) 15 (75%) Gender Male Medianage (range), years 44 (22–71) 21 (17–30) 34 ( 20–44) 25 (20–51) 38.3 (23–70) 36 (26.3–48.3) Age 19 Vaccine type Pfizer-BioNTech: 3 (42%) Moderna: 4 (57%) Pfizer BioNTech: 35 (83%) Moderna: 6 (14%) Moderna: 4 (80%) Comirnaty: 1 (20%) Pfizer BioNTech: 7 (30%) Moderna: 16 (70%) Pfizer BioNTech: 2 (50%) Moderna: 2 (50%) Pfizer BioNTech: 9 (45%) Moderna: 11 (55%) Vaccine type Second dose of Pfizer-BioNTech Comorbidities …”

“…One study, pooling cases of myocarditis from the USA, Israel, Singapore, and a few other countries, demonstrated that 83% of the patients developed myocarditis symptoms only after the second vaccine dose [9] . Additionally, a retrospective case series analyzing data from the Mayo Clinic COVID-19 Vaccine Registry elucidated that all seven cases occurred after the second dose [7] . Other studies that have reported myocarditis symptoms occurring post-second dose of COVID-19 mRNA vaccines reported rates hovering between 40% and 100%.…”

“…Most cases of myocarditis post-vaccination presented with elevated cardiac troponin levels along with simultaneous elevations in C-reactive protein (CRP), brain natriuretic peptide (BNP) or N-terminal prohormone BNP (NT-proBNP) [7] , [9] , [24] . Interestingly, abnormal electrocardiogram findings were seen in a few patients.…”