Table 1. Case definition of MIS-C [5,6,9]

	CSTE/CDC	WHO	KDCA
Age	< 21 years	0–19 years of age	0–19 years of age
Fever	Documented fever (≥ 38°C)	Fever > 3 days	Fever ≥ 38°C at least for 24 hours
Severity	Illness with clinical severity requiring hospitalization or resulting in death		Illness with clinical severity requiring hospitalization
Alternative diagnosis	A more likely alternative diagnosis is not present	No other obvious microbial cause of inflammation, including bacterial sepsis, staphylococcal or streptococcal shock syndromes	No other microbial cause of inflammation, including bacterial sepsis, staphylococcal or streptococcal toxic shock syndrome, or enteroviral myocarditis
Inflammation	CRP ≥ 3.0 mg/dL	Elevated markers of inflammation such as ESR, CRP, or procalcitonin	Elevated inflammatory markers (ESR, CRP, fibrinogen, procalcitonin, d-dimer, ferritin, LDH, IL-6, or neutrophil)Decreased lymphocyte or albumin
Organ involvement	New onset manifestations in ≥ 2 of the following categories1) Cardiac involvement1)2) Mucocutaneous involvement2)3) Shock4) Gastrointestinal involvement3)5) Hematologic involvement4)	At least two of the followings1) Cardiac involvement2) Mucocutaneous inflammation3) Hypotension or shock4) Gastrointestinal problems5) Evidence of coagulopathy	Two or more involved organ system1) Cardiac involvement2) Renal involvement3) Pulmonary involvement4) Hematologic involvement5) Gastrointestinal involvement6) Mucocutaneous involvement7) Neurologic involvement
Epidemiologic linkage with SARS-CoV-2	Detection of SARS-CoV-2 RNA, SARS-CoV-2 antigen or antibodies up to 60 days prior to or during hospitalization, or in a post-mortem specimenLikely contact with patients with COVID-19 in the 60 days prior	Evidence of COVID-19 (RT-PCR, antigen test, or serology positive)Likely contact with patients with COVID-19	Evidence of COVID-19 (RT-PCR, antigen test, or serology positive)Likely contact with patients with COVID-19 up to 4 weeks prior

indicated by left ventricular ejection fraction < 55 %, coronary artery dilatation, aneurysm, or ectasia, or troponin elevated above laboratory normal range.
indicated by rash, inflammation of the oral mucosa, conjunctival injection, conjunctivitis, or erythema of the hands or feet.
indicated by abdominal pain, vomiting, or diarrhea.
indicated by platelet count < 150,000 cells/µL or absolute lymphocyte count < 1,000 cells/µL.
MIS-C: Multisystem Inflammatory Syndrome in Children; CSTE/CDC: Council of State and Territorial Epidemiologists/Lefts for Disease Control and Prevention; WHO: World Health Organization; KDCA: Korea Disease Control and Prevention Agency; CRP: C-reactive Protein; ESR: erythrocyte sedimentation rate; LDH: lactate dehydrogenase; IL-6: interleukin-6; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; RNA: ribonucleic acid; COVID-19: coronavirus disease-2019; RT-PCR: reverse transcriptase polymerase chain reaction.