Table 2. Demographic and Clinical Characteristics of 23 Military Health System Patients With Myocarditis Following COVID-19 Vaccination, January-April 2021.
| Characteristic | No. (%) |
|---|---|
| Age, median (range), y | 25 (20-51) |
| Sex | |
| Male | 23 (100) |
| Female | 0 |
| Military status | |
| Currently serving | 22 (96) |
| Retired | 1 (4) |
| Proximate vaccine dose | |
| Second mRNA-1273 dose | 14 (61) |
| Second BNT162b2-mRNA dose | 6 (26) |
| First mRNA-1273 dose | 2 (9) |
| First BNT162b2-mRNA dose | 1 (4) |
| Time to symptom onset, mean (range), h | 50 (12-96) |
| Troponin levela | |
| Elevated | 23 (100) |
| Not elevated | 0 |
| Electrocardiogram findingsb | |
| Abnormal | 19 (83) |
| Normal | 4 (17) |
| Echocardiogram findingsc | |
| LVEF <50% | 4 (17) |
| LVEF ≥50% | 19 (83) |
| Coronary artery imaging | |
| Abnormal | 0 |
| Normal | 16 (70) |
| Not performed | 7 (30) |
| Cardiac MRId | |
| Abnormal | 8 (35) |
| Normal | 0 |
| Not performed | 15 (65) |
| SARS-CoV-2 PCR findings at presentation | |
| Positive | 0 |
| Negative | 19 (83) |
| Not performed | 4 (17) |
| Other viral testing at presentatione | |
| Positive | 0 |
| Negative | 13 (57) |
| Not performed | 10 (43) |
| History of prior SARS-CoV-2 infection | |
| Positive | 3 (13) |
| Negative | 20 (87) |
Abbreviations: LVEF, left ventricular ejection fraction; MRI, magnetic resonance imaging; mRNA, messenger RNA; PCR, polymerase chain reaction.
Inconsistencies in troponin types and laboratory sensitivity of testing preclude reporting combined quantified results.
Electrocardiogram findings included ST elevations, T-wave inversions, and nonspecific ST changes.
Echocardiogram findings are reported as LVEF; no structural abnormalities were noted in any patients.
All abnormal cardiac MRIs reportedly met current Lake Louise criteria for myocarditis, with subepicardial late gadolinium enhancement and/or focal myocardial edema.
Testing for other acute viral infections varied in each case; panels included some or all of these pathogens: coxsackie viruses, cytomegalovirus, Epstein-Barr virus, hepatitis A virus, hepatitis B virus, hepatitis C virus, herpes simplex virus, human herpesvirus 6, HIV, influenza viruses, and parvoviruses.