The purpose of this study is to learn about the safety and effects of the vaccine (called COMIRNATY) for the potential prevention of COVID-19. This study is seeking participants who:
1. Are age \<21 years.
2. Have presentation to participating medical center with evaluation in Emergency Room and/or hospitalization.
3. Received any dose(s) of COMIRNATY within 21 days of symptom onset.
4. Meet criteria of Centers for Disease Control and Prevention case definition of probable or confirmed myocarditis/pericarditis
5. Are capable of giving signed informed consent/assent (by parents/legal guardians of minors and/or patients), which includes compliance with the requirements and restrictions listed in the Informed Consent/Assent Document and in this protocol OR meets criteria for waiver of consent.
This study will examine the potential long-term effects associated with myocarditis/pericarditis following vaccination with COMIRNATY. The association of myocarditis/pericarditis in participants who received the study vaccine (COMIRNATY) compared with those associated with COVID-19 will also be examined. This will help us determine if COMIRNATY is safe and effective, and if there is a myocarditis/pericarditis association that should be noted. Participants will take part in this study for up to 5 years. During this time, they will receive complete cardiac imaging tests, and have follow up visits per guidance stated in the study protocol.