| Age | ≤ 19 years | < 21 years | ≤ 19 years |
| Fever | ≥ 3 days | ≥ 24 hours | ≥ 38.0°C for ≥ 24 hours |
| Multisystem involvement | 1. Rash or bilateral nonpurulent conjunctivitis or mucocutaneous inflammation signs (oral, hands, or feet)2. Hypotension or shock3. Features of myocardial dysfunction, pericarditis, valvulitis, or coronary abnormalities (including echocardiography findings or elevated troponin/NT-proBNP)4. Evidence of coagulopathy (by PT, aPTT, elevated D-dimers)5. Acute gastrointestinal problems (diarrhea, vomiting, or abdominal pain) | Multisystem (> 2) organ involvement (cardiac, kidney, respiratory, hematologic, gastrointestinal, dermatologic, or neurological) | 2 or more organs (cardiac, renal, respiratory, hematologic, gastrointestinal, dermatologic or neurological disorder) |
| Laboratory evidence of inflammation | Elevated markers of inflammation such as ESR, CRP, or procalcitonin | ≥ 1 of the following: an elevated CRP level, ESR, fibrinogen, procalcitonin, D-dimer, ferritin, lactic acid dehydrogenase, or IL-6; elevated neutrophils; reduced lymphocytes; and low albumin | Elevated ESR, CRP, fibrinogen, procalcitonin, D-dimer, ferritin, LDH, and IL-6; neutrophilia; lymphopenia; hypoalbuminemia |
| Requiring hospitalization | No | Yes | Yes |
| Evidence of COVID-19 | RT-PCR, antigen test, or serology positive, or likely contact with patients with COVID-19 | RT PCR, antigen test, serology test, or contact with patients with COVID-19 within 4 weeks | positive PCR, antibody or antigen test, or contact with patients with COVID-19 within 4 weeks |
| Other plausible diagnosis | No other obvious microbial cause of inflammation | No alternative plausible diagnoses | Exclusion of any other microbial cause of inflammation |