Table 1.

Case Definitions

The Centers for Disease Control and Prevention (CDC) Definition–Multisystem Inflammatory Syndrome in Children •An individual aged <21 years presenting with fever,a laboratory evidence of inflammation,b and evidence of clinically severe illness requiring hospitalization, with multisystem (≥2) organ involvement (cardiac, renal, respiratory, hematologic, gastrointestinal, dermatologic or neurologic); AND •No alternative plausible diagnoses; AND •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 weeks before the onset of symptoms. The World Health Organization Definition–Multisystem Inflammatory Syndrome in Children Children and adolescents 0-19 years of age with fever ≥ 3 days AND 2 of the following: •Rash or bilateral nonpurulent conjunctivitis or mucocutaneous inflammation signs (oral, hands or feet). •Hypotension or shock. •Features of myocardial dysfunction, pericarditis, valvulitis, or coronary abnormalities (including echocardiography findings or elevated Troponin/NT-pro-BNP), •Evidence of coagulopathy (by PT, PTT, elevated D-dimers). •Acute gastrointestinal problems (diarrhea, vomiting, or abdominal pain). AND Elevated markers of inflammation such as ESR, C-reactive protein, or procalcitonin. AND No other obvious microbial cause of inflammation, including bacterial sepsis, staphylococcal or streptococcal shock syndromes. AND Evidence of COVID-19 (RT-PCR, antigen test, or serology positive), or likely contact with patients with COVID-19. CDC Definition-Kawasaki Disease: For epidemiologic surveillance, CDC defines a case of Kawasaki disease as illness in a patient with fever of ≥ 5 days’ duration (or fever until the date of administration of intravenous immunoglobulin if it is given before the fifth day of fever), and the presence of at least 4 of the following 5 clinical signs: •Rash •Cervical lymphadenopathy (at least 1.5 cm in diameter) •Bilateral conjunctival injection •Oral mucosal changes •Peripheral extremity changes Patients whose illness does not meet the above Kawasaki disease case definition but who have fever and coronary artery abnormalities are classified as having atypical or incomplete Kawasaki disease.

COVID-19 = coronavirus disease 2019; NT-pro-BNP = N-terminal pro B-type natriuretic peptide; PT = prothrombin time; PTT = partial thromboplastin time; RT-PCR = reverse transcription polymerase chain reaction; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2.

From: Centers for Disease Control and Prevention. Kawasaki case definition. https://www.cdc.gov/kawasaki/case-definition.html

World Health Organization Multisystem inflammatory syndrome in children and adolescents temporally related to COVID-19. https://www.who.int/news-room/commentaries/detail/multisystem-inflammatory-syndrome-in-children-and-adolescents-with-covid-19

Centers for Disease Control and Prevention. Multisystem inflammatory Syndrome in Children (MIS-C) associated with coronavirus disease 2019 (COVID-19) Control https://emergency.cdc.gov/han/2020/han00432.asp

^aFever ≥ 38.0°C for ≥ 24 hours, or report of subjective fever lasting ≥ 24 hours.

^bIncluding, but not limited to, 1 or more of the following: an 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.¹⁴