Patient is 22 year-old, admitted to the Cardiology 3  Emergency Department with acute myocarditis shortly following the receipt of his 2nd Moderna COVID-19 vaccination.   He has a remote history of acute pericarditis (01/12/2014) following viral illness, which was treated with high dose ibuprofen 800 mg t.i.d.  At that time, he presented with retrosternal chest pain worse with laying down and fever/myalgia, rigors and chills (T 103.3°F) with laboratory findings consistent with leukocytosis 17.3, elevated inflammatory markers (CRP 43, but normal ESR 12) with a negative influenza screen.  ECG demonstrated diffuse ST wave elevations in leads I, II, aVF, V1-V6.  He had resolution of symptoms with NSAID treatment.   On this occasion, he presented with non-radiating retrosternal chest pain not responding to Ibuprofen 800 mg.  At the ED, ECG demonstrated diffuse ST elevation, troponinemia 629/725/712/1319, elevated inflammatory markers (CRP 38.2, ESR 19).  He had normal D-dimer and SARS-CoV-2 PCR was undetected.  A cardiac MRI was obtained that demonstrated patchy subepicardial enhancement in the mid-apical lateral-anterolateral myocardium, suggestive of myocarditis.  EKG showed diffuse ST elevation.  He was treated with Toradol and fentanyl for pain management with improvement of symptoms.  He was then admitted to Cardiology 3 for further evaluation and management.   Upon admission, Infectious Disease was consulted given the novelty of his presenting symptoms and findings.  Extensive evaluation including connective tissue cascade, respiratory viral panel and tick bone panel have not yielded any significant findings.  They suspected this could be related to his recent COVID vaccine given that there have been reports of myocarditis that have occurred following COVID-19 messenger RNA vaccinations, though it is not clear whether there is a definite cause or effect.  Moreover, the association of myocarditis and the messenger RNA COVID-19 vaccinations appears to be controversial, not supported by recent FDA reports.  All in all, the Infectious Disease team recommended no specific therapies, but the case should be reported as a possible adverse event associated with the recent Moderna vaccination to VAERS.  The center where the patient received this vaccination should make this report. Emergency Management Director was notified to report the event.  They also felt that it may be reasonable to avoid the Moderna and perhaps even the Pfizer messenger RNA COVID-19 vaccination in the future to be conservative.   While inpatient, his troponin level continued to trend up and peaked at 1707.  An EKG was repeated and showed improvement in ST elevation from his initial EKG with no other acute changes.  His case was discussed with Dr., who felt that a steroid taper would be appropriate.  Additional chest pain was treated with PRN Ibuprofen 600 mg QID.  After initiation of steroids, troponin markedly improved to 706.  Due to his history of impaired fasting glucose, his blood glucose levels were monitored q.i.d.  While slightly elevated, he did not require any sliding scale insulin while inpatient.  We will plan to have his primary care provider assess his glucose level at his follow-up visit.  Additionally, while receiving NSAIDs and steroids, his blood pressure was elevated to the 150s to 160 systolic.  He was initiated on Coreg prior to dismissal.   He was dismissed on 04/29/2021 given improving troponin and no concerning arrhythmias on continuous telemetry monitoring.  He will follow up in the Cardiomyopathy Clinic in 3 months with a repeat cardiac MRI and stress ECG.  We have recommended the patient to avoid heavy lifting or strenuous activity for the next 3 months until seen by the cardiomyopathy Clinic.  He was provided with education and a letter delineating work restrictions.