myocarditis; This is a literature report for the following literature source(s):  Background: Rare cases of myocarditis have been reported in adults following COVID-19 vaccination, with most cases occurring in males <30 years old. Since the authorization to administer the Pfizer-BioNTech COVID-19 vaccine in those as young as 12 years of age, suspected myocarditis temporally related to the vaccine has also been reported in adolescents. Myocarditis has been associated with other vaccines, such as smallpox and influenza, though data are limited regarding symptoms, clinical course, and short-term outcomes of suspected myocarditis following COVID-19 vaccination. On June 23, 2021, the Centers for Disease Control and Prevention's (CDC) Advisory Committee on Immunization Practices reported a likely link between mRNA COVID-19 vaccination and myocarditis, particularly in those </ 39 years old. The authors aim to describe a large case series of suspected myocarditis temporally related with the COVID-19 vaccine in adolescents and young adults <21 years old. METHODS: The data that support the findings of this study are available from the corresponding author on reasonable request. Patients, the authors collected data retrospectively for adolescents and young adults <21 years old who presented with symptoms, laboratory markers, and/or imaging findings concerning for myocarditis within 30 days of COVID-19 vaccination from 26 pediatric medical centers prior to July 4, 2021. The authors included patients with clinically suspected myocarditis who had elevated troponin levels and abnormal electrocardiograms (ECGs), cardiac function on non-invasive imaging, or findings consistent with myocarditis on cardiac magnetic resonance imaging (cMRI), including myocardial edema or late gadolinium enhancement. Cases of suspected vaccine associated myocarditis (VAM) were categorized as probable or confirmed using the CDC case definitions. The authors excluded patients in whom troponin levels were not measured or had normal levels, or who had a plausible alternative etiology for suspected myocarditis. Evaluations for alternative etiologies were at the discretion of sites, based on local assessments. If a patient presented with symptoms and findings suggestive of myocarditis after more than one vaccine dose, the more severe presentation was added to the aggregate data for analysis. Data obtained: The authors collected de-identified and targeted demographic, clinical, laboratory, imaging and ECG, and short-term outcomes data. Prior COVID-19 infection was defined as having a personal history of laboratory- confirmed SARS CoV-2 testing and/or having had symptoms and immediate household family member(s) who tested positive for SARS CoV-2 but the patient was not tested. Left ventricular systolic function was categorized as normal if graded as normal by local assessment, or if left ventricular ejection fraction (LVEF) was >/55%; mildly decreased systolic function was defined as LVEF <45-54%, moderately decreased if 35-44%; and severely decreased if <35%. The decision and the timing to obtain cMRIs were at the discretion of the local clinical teams, and cMRIs were performed using local protocols. Data on cMRIs were collected retrospectively from clinical reports. Statistical analyses: Descriptive statistics include percentages for discrete variables and median values with range or interquartile range for continuous variables. Fisher's exact or Wilcoxon-Rank-Sum tests were used to compare markers of illness severity in patients who did vs. did not undergo cMRI, and time to cMRI in those that were normal vs. abnormal. Markers of illness severity included need for intensive care unit (ICU) stay, left ventricular dysfunction on echocardiogram, and troponin I levels, which were performed more frequently than troponin T. All analyses were performed using Stata 11.2 (Result: As of July 4, 2021, 146 episodes of clinically suspected VAM occurred in 145 adolescents and young adults <21 years old at 26 centers, with 6 patients excluded due to lack of abnormal troponin. Thus, 140 episodes in 139 patients were analyzed. One patient presented with suspected myocarditis following both doses of the Pfizer-BioNTech vaccine, with a more severe course after the 2nd dose; data from his 2nd episode are included in the aggregate analysis, as detailed below. The majority of patients (N=92, 66.2%), (N=96, 69.1%), and male (N=126, 90.6%) with a median age of 15.8 years (range 12.1-20.3, IQR 14.5-17.0). Based on symptoms, laboratory and imaging data, 49 (35.0%) episodes of suspected myocarditis met criteria for confirmed myocarditis based on CDC classification, and the remaining 91 (65.0%) would be classified as probable. No patients underwent endomyocardial biopsy. Of the 140 episodes of clinically suspected VAM, 124 (88.6%) were evaluated with SARS CoV-2 PCR testing at the time of presentation, all of which were negative. Two patients had positive PCR testing within 32 days of presentation of suspected myocarditis, and thus were not tested again. Fifteen (10.7%) patients had evidence of previous COVID-19 infection by history (N=5), positive nucleocapsid antibodies (N=5), or both (N=5). Prior COVID-19 infection occurred <1 month to up to 10 months before the suspected myocarditis episode in the 10 patients with a known history. The majority (N=94, 67.6%) had no history of prior infection and/or had negative nucleocapsid antibodies to COVID-19, though in 30 patients (21.6%) the history was unknown and no nucleocapsid antibody testing was performed. Of the 12 patients who presented with myocarditis after the 1st dose of vaccine, six had a history of prior COVID-19 infection or had the presence of nucleocapsid antibodies. Evaluation for alternative microbial etiologies for suspected myocarditis varied, with no plausible alternatives determined by centers. None had a prior history of multisystem inflammatory syndrome in children (MIS-C).  A 17-year-old male patient with a history of obesity and hyperlipidemia and no known previous history of COVID-19 infection had presumed myocarditis after both the first and second doses of the Pfizer-BioNTech vaccine. He had onset of chest pain 20 days after his first dose and presented to the emergency department; laboratory tests showed a peak troponin I of 0.45 ng/mL. No testing for acute or previous COVID-19 infection was performed, and no other causes for myocarditis were evaluated at that time. His ECG and echocardiogram were normal, and cMRI was not performed. He was treated with NSAIDs as an outpatient. His chest pain resolved, with a decrease in troponin level to 0.3 ng/mL 3 days after presentation. Of note, he also had a history of suspected myocarditis at age 10 years, with symptoms of fever, sore throat, and chest pain. At that time, he was admitted to the ICU, with troponin I level of 0.78 ng/mL, normal ECG, and normal function by echocardiography. No cMRI was performed associated with this episode.; Sender's Comments: The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.,Linked Report(s) : US-PFIZER INC-202101837752 same reporter and product, and event; different patient;