Case Definitions and Reporting

An illness characterized by all of the following, in the absence of a more likely alternative diagnosis*

• Subjective or documented fever (temperature ≥38.0⁰ C)
• Clinical severity requiring hospitalization or resulting in death
• Evidence of systematic inflammation indicated by C-reactive protein ≥3.0 mg/dL (30 mg/L
• New onset manifestations in at least two of the following categories:

1. Cardiac involvement indicated by:
   1. Left ventricular ejection fraction <55% OR
   2. Coronary artery dilatation, aneurysm, or ectasia, OR
   3. Troponin elevated above laboratory normal range, or indicated as elevated in a clinical note
2. Mucocutaneous involvement indicated by:
   1. Rash, OR
   2. Inflammation of the oral mucosa (e.g., mucosal erythema or swelling, drying or fissuring of the lips, strawberry tongue), OR
   3. Conjunctivitis or conjunctival injection (redness of the eyes), OR
   4. Extremity findings (e.g., erythema [redness] or edema [swelling] of the hands or feet)
3. Shock**
4. Gastrointestinal involvement indicated by:
   1. Abdominal pain, OR
   2. Vomiting, OR
   3. Diarrhea
5. Hematologic involvement indicated by:
   1. Platelet count <150,000 cells/μL, OR
   2. Absolute lymphocyte count (ALC) <1,000 cells/μL

*If documented by the clinical treatment team, a final diagnosis of Kawasaki Disease should be considered an alternative diagnosis. These cases should not be reported to national MIS-C surveillance.

**Clinician documentation of shock meets this criterion.

• Detection of SARS-CoV-2 RNA in a clinical specimen*** up to 60 days prior to or during hospitalization, or in a post-mortem specimen using a diagnostic molecular amplification test (e.g., polymerase chain reaction [PCR]), OR
• Detection of SARS-CoV-2 specific antigen in a clinical specimen*** up to 60 days prior to or during hospitalization, or in a post-mortem specimen, OR
• Detection of SARS-CoV-2 specific antibodies^ in serum, plasma, or whole blood associated with current illness resulting in or during hospitalization

***Positive molecular or antigen results from self-administered testing using over-the-counter test kits meet laboratory criteria.

^Includes a positive serology test regardless of COVID-19 vaccination status. Detection of anti-nucleocapsid antibody is indicative of SARS-CoV-2 infection, while anti-spike protein antibody may be induced either by COVID-19 vaccination or by SARS-CoV-2 infection

• Close contact‡ with a confirmed or probable case of COVID-19 disease in the 60 days prior to hospitalization.

‡Close contact is generally defined as being within 6 feet for at least 15 minutes (cumulative over a 24-hour period). However, it depends on the exposure level and setting; for example, in the setting of an aerosol generating procedure in healthcare settings without proper personal protective equipment (PPE), this may be defined as any duration.

• A person whose death certificate lists MIS-C or multisystem inflammatory syndrome as an underlying cause of death or a significant condition contributing to death.

• No alternative diagnosis (e.g. bacterial sepsis, exacerbation of a chronic medical condition) AND

• At least THREE of the following clinical criteria occurring prior to hospitalization or within the first THREE days of hospitalization. At least ONE must be a primary clinical criterion.

• Severe cardiac illness** (Includes myocarditis, pericarditis, coronary artery dilatation/aneurysm, new-onset right or left ventricular dysfunction [LVEF<50%], 2nd/3rd degree AV block, or ventricular tachycardia.)
• Rash AND non-purulent conjunctivitis

**Cardiac arrest alone does not meet this criterion

• New-onset neurologic signs and symptoms (Includes encephalopathy in a patient without prior cognitive impairment, seizures, meningeal signs, or peripheral neuropathy including Guillain-Barré syndrome)
• Shock or hypotension not attributable to medical therapy (e.g., sedation, renal replacement therapy)
• Abdominal pain, vomiting, or diarrhea
• Thrombocytopenia (platelet count <150,000/μL)

• Evidence of SARS-CoV-2 infection AND
  • Positive SARS-CoV-2 nucleic acid amplification (NAAT), serology, or antigen test

• Evidence of systemic inflammation
  • Elevated levels of at least 2 of the following: C-reactive protein (CRP), ferritin, interleukin-6 (IL-6), erythrocyte sedimentation rate (ESR), procalcitonin