Determinants of COVID-19 Vaccine-Induced Myocarditis Requiring Hospitalization

Objective: To characterize determinants of COVID-19 vaccine-induced myocarditis requiring hospitalization in Vaccine Adverse Event Reporting System (VAERS) domestic data.

Design: Cross sectional, descriptive analysis of VAERS reports of COVID-19 vaccine-induced myocarditis requiring hospitalization in individuals aged 3 months to 98 years of age.

Participants: All individuals who submitted an adverse event (AE) report to VAERS associated with a diagnosis of myocarditis from December 14, 2020 through March 18, 2022.

Results: 3569/3594 (99.3%) cases of COVID-19 vaccine-induced myocarditis requiring hospitalization reports analyzed in the VAERS domestic data set were not co-associated with COVID-19 respiratory illness in accordance with either ‘negative’ polymerase chain reactions (PCR) to detect SARS-CoV-2, COVID-19 diagnosis, or both. Rates of hospitalization were high with 84% of all myocarditis reports associated with hospitalization in the 0-19 age group and 70.9, in general. Myocarditis in the context of co-presentation of elevated cardiac troponin (cTn), chest pain (CP), abnormal cardiac imaging , electrocardiogram ST segment elevation (STE) and abnormal C-reactive protein levels (CRP) was reported in the context of hospitalization in 92.2%, 85.5%, 93.5%, 93.9% and 90.3%, respectively, in children ages 0-19. 79% of all myocarditis requiring hospitalization reports were made within 7 days of injection and 48% were reported within 48 hours of injection. 90% of all myocarditis requiring hospitalization reports and 58% of reports were filed within 7 days and 48 hours, respectively in children ages 0-19. Higher reporting rates of troponin elevation, ST segment elevation and CRP abnormalities were found in 12-18-year-olds when compared to the next highest rates found in 19-29-year-olds (chi-sq; p = 0.00000000; p = 0.00000000; p = 0.00000006).  The independent predictors of hospitalization were as follows: male gender, OR=1.81, 95% CI 1.68-1.95, p<0.005; age (0-19 vs. 19+) OR=2.32, 95% CI 2-2.69, p<0.005; elevated troponin (12-18 vs. all other age groups), OR=4.63, 95% CI 3.59-5.99, p<0.005; an ST elevation (12-18 vs. all other age groups), OR=4.62, 95% CI 2.99-7.13, p<0.005.

Conclusions: Among those with COVID-19 vaccine-induced myocarditis, the majority were hospitalized, and the independent predictors of hospitalization were age, male gender, positive troponin, and ST-segment elevation on the ECG. Temporal proximity of reporting to injection date and significantly higher reporting rates of cardiac troponin, electrocardiogram ST segment elevation and abnormal C-reactive proteins in young individuals (12-18) in the context of myocarditis requiring hospitalization indicate that these particular pathognomonic markers may be linked to incipient heart failure whereby the injury due to the injection is the reason for the hospitalization, and should always be measured and used as diagnostic markers for COVID-19 vaccine-induced myocarditis.