Table 5. MIS-C groups (Class 1, 2, and 3) reported to the CDC [19] and their comparison with this study

	Class 1, n = 203 (classic MIS-C)	Class 2, n = 169 (acute COVID-19)	Class 3, n = 198 (KD-like MIS-C)	This study, n = 22
Clinical
Age, years	9	10	6	9
Male sex, %	57.1	52.1	56.6	50.0
Asian race, %	0.6	2.3	5.6	100.0
Complete KD, %	4.9	3.0	6.6	50.0
PCR (–) & Ab (+)1), %	68.0	0.0	63.1	40.9
Organ involvement, %
Cardiac involvement	55.3	46.0	21.0	54.5
Mucocutaneous involvement	76.8	51.5	81.3	95.5
Shock	75.9	28.4	0.0	27.3
Gastrointestinal involvement	97.5	86.4	87.9	90.9
Thrombocytopenia	41.4	26.6	23.7	59.1
Treatment and outcomes, %
IVIG	87.9	62.7	87.5	86.4
ICU admission	84.2	62.1	44.4	22.7
Ventilator care (ARDS)	6.9	10.1	1.5	4.5
Coronary complications	21.1	15.8	18.2	22.7
Mortality	0.5	5.3	0.0	0.0

PCR (–) & Ab (+) indicate that there is no more virus but a serious post-infectious inflammatory response, which is the key pathogenesis of MIS-C.
MIS-C: multisystem inflammatory syndrome in children; CDC: Centers for Disease Control and Disease Prevention; COVID-19: coronavirus disease 2019; KD: Kawasaki disease; PCR: polymerase chain reaction; Ab: antibodies; IVIG: intravenous immunoglobulin; ICU: intensive care unit; ARDS: acute respiratory distress syndrome.