Data on features of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in children and adolescents are scarce. We report preliminary results of an Italian multicentre study comprising 168 laboratory-confirmed paediatric cases (median: 2.3 years, range: 1 day–17.7 years, 55.9% males), of which 67.9% were hospitalised and 19.6% had comorbidities. Fever was the most common symptom, gastrointestinal manifestations were frequent; two children required intensive care, five had seizures, 49 received experimental treatments and all recovered.

We describe 2 children with persistent fever and profuse diarrhea who developed signs of mucocutaneous involvement (conjunctivitis, fissured lips, skin rash, erythema, and edema of the hands and feet). Blood tests revealed elevated markers of inflammation, lymphopenia, thrombocytopenia, and complement consumption. Afterward, diffuse edema with hypoalbuminemia appeared in the context of a capillary leak syndrome. In both patients, repeated nasal swabs were negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but each patient had high titers of immunoglobulin G and immunoglobulin M against the SARS-CoV-2 virus. The negative PCR results in the presence of immunoglobulin M and immunoglobulin G suggested that the inflammatory response developed in the late phase of viral infection, when SARS-CoV-2 was not detectable in the upper airway. In this report, we describe patients with what we propose to name as SARS-CoV-2–induced Kawasaki-like hyperinflammatory syndrome. SARS-CoV-2–induced Kawasaki-like hyperinflammatory syndrome seems to be caused by a delayed response to SARS-CoV-2. It resembles Kawasaki disease complicated by macrophage activation syndrome, although it has peculiar features, such as prodromal diarrhea, capillary leak syndrome, and myocardial dysfunction. Intravenous corticosteroid treatment appears to be helpful.

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