This case series examines cardiac MRI findings in four children and adolescents admitted to intensive care in April 2020 for multisystem inflammatory syndrome and Kawasaki disease-like features related to COVID-19. Acute myocarditis occurred less than 1 week after onset of fever and gastrointestinal symptoms. Physical examination showed rash and cheilitis/conjunctivitis. All patients recovered after intravenous immunoglobulin therapy. SARS-CoV-2 RT-PCR was negative on nasopharyngeal, stool, and respiratory samples and was positive on serology. Cardiac MRI showed diffuse myocardial edema on T2-STIR sequences and native-T1 mapping, with no evidence of late gadolinium enhancement suggestive of replacement fibrosis or focal necrosis. These findings favor post-infectious myocarditis in children and adolescents with COVID-19.

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Background: Ten months after its appearance in December 2019, SARS-CoV-2 has infected more than 25 million patients worldwide. Because children were first identified as potential spreaders of the virus, schools were closed in several countries. However, it rapidly became evident that the number of hospitalized children infected by SARS-CoV-2 was dramatically lower than that of adults. To date, only hypotheses have been raised to explain this difference, so it is of great importance to describe the presentation of this disease among children. Here, we describe a wide spectrum of COVID-19 manifestation in children in a dedicated pediatric unit in France. Methods: Patients hospitalized with COVID-19 who were diagnosed on the basis of either positive SARS-CoV-2 RT-PCR in nasopharyngeal swabs and/or typical aspects in chest-computed tomography (CT) were included between March and May 2020 in Paris. Results: Twenty-three patients were included on the basis of positive RT-PCR (n = 20) and/or typical aspects in CT (n = 4). The median age was 4.9 years [0.1–17.6]. Patients were grouped by age (<2 years old: n = 14, 61%; 2–10 years old: n = 2, 9%; >10 years old: n = 7, 30%). Overweight or obesity was reported in only three patients. At presentation, the most frequent symptom in the overall cohort was fever (n = 18, 78%), followed by acute rhinitis (n = 9, 64%) and cough (n = 7, 50%) in the under 2-year-old group and cough (n = 4, 57%), fatigue, dyspnea and abdominal pain (n = 3, 43% each) in the over 10-year-old group. Five patients required ICU treatment, four of whom were aged >10 years, two presented with acute myocarditis, and two were sickle cell disease patients who presented with acute chest syndrome. Discussion and conclusion: The youngest patients seem to present milder forms of COVID-19 without the need for ICU treatment and with a shorter length of hospitalization. More severe evolutions were observed in teenagers, with, however, favorable outcomes. Given the context of closed schools and confinement, the infection of these children suggests intra-familial transmission that needs to be further assessed. This description might help to understand the intriguing differences in COVID-19 severity across age-classes.