41 children from Italy with MIS-C and 10 from Stockholm have been compared with 28 children diagnosed with Kawasaki before the COVID-19 pandemic. They map out the differences and similarities.
SARS-CoV-2 infection is typically very mild and often asymptomatic in children. A complication is the rare Multisystem Inflammatory Syndrome in Children (MIS-C) associated with COVID-19, presenting 4-6 weeks after infection as high fever, organ dysfunction and strongly elevated markers of inflammation. The pathogenesis is unclear but has overlapping features with Kawasaki disease suggestive of vasculitis and a likely autoimmune etiology. We apply systems-level analyses of blood immune cells, cytokines and autoantibodies in healthy children, children with Kawasaki disease enrolled prior to COVID-19, children infected with SARS-CoV-2 and children presenting with MIS-C. We find that the inflammatory response in MIS-C differs from the cytokine storm of severe acute COVID-19, shares several features with Kawasaki disease, but also differs from this condition with respect to T-cell subsets, IL-17A and biomarkers associated with arterial damage. Finally, autoantibody profiling suggests multiple autoantibodies that could be involved in the pathogenesis of MIS-C.Препринт