ISG15 and COVID-19: Analysis of type I IFNs inducible genes expression performed in granulocytes and PBMCs showed increased transcription of ISG15 and IFIT1 mRNAs in cells of the COVID-19 patients, while ISG15 and IFIT1 mRNAs were detected in MIS-C at levels comparable to adult healthy controls (Figures 2C–F).