Multisystem Inflammatory Syndrome in Children (MIS-C); case study; child; clinical article; clinical feature; clinical laboratory; conference abstract; coronary artery; coronavirus disease 2019; ethnic group; female; fever; follow up; gene amplification; hospitalized child; human; incidence; intensive care unit; left ventricular systolic dysfunction; male; nonhuman; pediatric multisystem inflammatory syndrome; pericardial effusion; polymerase chain reaction; prognosis; school child; Severe acute respiratory syndrome coronavirus 2; treatment response; antigen