Table 1.

Diagnostic criteria for MIS-C as per the WHO and CDC [10, 11]

CDC case definition [10]	WHO case definition [11]
All 4 criteria must be met	All 6 criteria must be met
1. Age <21 years	1. Age 0–19 years
2. Clinical presentation consistent with MIS-C, including all of the following	a − Fever: documented fever >38.0°C (100.4°F) for ≥24 h or report of subjective fever lasting ≥24 h	2. Fever for ≥3 days
b − Multisystem involvement: 2 or more organ systems involved  Cardiovascular (e.g., shock, elevated troponin, elevated  BNP, abnormal echocardiogram, arrhythmia)  Respiratory (e.g., pneumonia, ARDS, pulmonary embolism)  Renal (e.g., AKI, kidney failure)  Neurologic (e.g., seizure, stroke, aseptic meningitis)  Haematologic (e.g., coagulopathy)  Gastrointestinal (e.g., abdominal pain, vomiting, diarrhoea, elevated liver enzymes, ileus, gastrointestinal bleeding)  Dermatologic (e.g., erythroderma, mucositis, other rash)	3. Clinical signs of multisystem involvement (at least 2 of the following) Rash, bilateral non-purulent conjunctivitis, or mucocutaneous inflammation signs (oral, hands, or feet) Hypotension or shock Cardiac dysfunction, pericarditis, valvulitis, or coronary abnormalities (including echocardiographic findings or elevated troponin/BNP) Evidence of coagulopathy (prolonged PT or PTT; elevated D-dimer) Acute gastrointestinal symptoms (diarrhoea, vomiting, or abdominal pain)
c − Laboratory evidence of inflammation including, but not limited to, any of the following  Elevated CRP  Elevated ESR  Elevated fibrinogen  Elevated PCT  Elevated D-dimer  Elevated ferritin  Elevated LDH  Elevated IL-6 level  Neutrophilia  Lymphocytopaenia  Hypoalbuminemia	4. Elevated markers of inflammation (e.g., ESR, CRP, or PCT)
d − Severe illness requiring hospitalization	–
3. No alternative plausible diagnoses	5. No other obvious microbial cause of inflammation, including bacterial sepsis and staphylococcal/streptococcal toxic shock syndromes
4. Recent or current SARS-CoV-2 infection or exposure	6. Evidence of SARS-CoV-2 infection
Any of the following	Any of the following
Positive SARS-CoV-2 RT-PCR	Positive SARS-CoV-2 RT-PCR
Positive serology	Positive serology
Positive antigen test	Positive antigen test
COVID-19 exposure within the 4 weeks prior to the onset of symptoms	Contact with an individual with COVID-19

HAN, Health Alert Network; ESR, erythrocyte sedimentation rate; LDH, lactate dehydrogenase.