Table 5.

Case definitions of MIS-C

Institution	US Centers for Disease Control and Prevention196	World Health Organization201	Royal College of Pediatrics and Child Health194
Age group	An individual aged <21 y presenting with the following:	Children and adolescents 0–19 y of age with the following:	A child presenting with the following:
Fever	fever ≥38.0°C for ≥24 h, or report of subjective fever lasting ≥24 h	fever ≥3 d	persistent fever >38.5⁰C
	AND	AND	AND
Inflammation	Laboratory evidence of inflammation including, but not limited to, 1 or more of the following: elevated C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), fibrinogen, procalcitonin, D-dimer, ferritin, lactic acid dehydrogenase (LDH), or interleukin 6 (IL-6), elevated neutrophils, reduced lymphocytes and low albumin	Elevated markers of inflammation such as ESR, CRP, or procalcitonin	Inflammation (neutrophilia, elevated CRP, and lymphopenia)
	AND	AND	AND
Severity of illness	Evidence of clinically severe illness requiring hospitalization
	AND
Organ system involvement	With multisystem (≥2) organ involvement (cardiac, renal, respiratory, hematologic, gastrointestinal, dermatologic, or neurologic)	2 of the following: (1) Rash or bilateral nonpurulent conjunctivitis or muco-cutaneous inflammation signs (oral, hands or feet). (2) Hypotension or shock. (3) Features of myocardial dysfunction, pericarditis, valvulitis, or coronary abnormalities (including echocardiogram findings or elevated troponin/NT-proBNP. (4) Evidence of coagulopathy (by PT, PTT, elevated d-Dimers). (5) Acute gastrointestinal problems (diarrhea, vomiting, or abdominal pain).	Evidence of single or multi-organ dysfunction (shock, cardiac, respiratory, renal gastrointestinal or neurologic disorder)
	AND	AND	AND
			with additional featuresa
			AND
Alternative explanations	No alternative for plausible diagnoses	No other obvious microbial cause of inflammation, including the following:	Exclusion of any other microbial cause including the following:
		Bacterial sepsis	Bacterial sepsis
		Staphylococcal or streptococcal shock syndromes	Staphylococcal or streptococcal shock syndromes
			Infections associated with myocarditis (such as enterovirus)
	AND	AND	AND
Virologic testing	Positive for current or recent SARS-CoV-2 infection by RT-PCR, serology, or antigen test; or exposure to a suspected or confirmed COVID-19 case within the 4 wk before the onset of symptoms	Evidence of COVID-19 (RT-PCR, antigen test or serology positive), or likely contact with patients with COVID-19	SARS-CoV-2 PCR testing may be positive or negative
Additional comments	Some individuals may fulfill full or partial criteria for Kawasaki disease but should be reported if they meet the case definition for MIS-C		This may include children fulfilling full or partial criteria for Kawasaki disease
	Consider MIS-C in any pediatric death with evidence of SARS-CoV-2 infection

Abbreviations: COVID-19, coronavirus disease 2019; MIS-C, multisystem inflammatory syndrome in children; NT-proBNP, N-terminal pro brain natriuretic peptide; PT, prothrombin time; PTT, partial thromboplastin time; RT-PCR, reverse-transcriptase polymerase chain reaction; SARS-CoV-2, severe acute respiratory distress syndrome coronavirus 2.

^aAdditional features: abnormal fibrinogen, high D-dimer, high ferritin, hypoalbuminemia, acute kidney injury, anemia, coagulopathy, high interleukin (IL)-10, high IL-6, proteinuria, raised creatine kinase, raised lactate dehydrogenase, raised triglycerides, raised troponin, thrombocytopenia, transaminitis.