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Multisystem Inflammatory Syndrome in Children (Mis-C) with Covid-19 Infection
Essentials
- In children, the COVID-19 infection caused by the SARS-CoV-2 virus causes mostly mild symptoms or even none. Most patients only have mild upper respiratory tract symptoms.
- Nevertheless, paediatric patients have been described with a rare and serious inflammatory syndrome associated with COVID-19 infection. In the international literature, the syndrome usually goes by the abbreviation MIS-C (Multisystem Inflammatory Syndrome in Children).
- Its symptoms resemble those of Kawasaki disease Kawasaki Disease. It involves serious cardiovascular symptoms, and patients often need intensive care.
- The pathophysiology is unclear but the syndrome is believed to be due to an abnormally delayed immune response to COVID-19 infection.
Epidemiology
- MIS-C is a rare syndrome developing in less than 1% of children about 3-5 weeks after COVID-19 infection.
- In a US study, its incidence in patients below 21 years of age was estimated at about 2/100 000.
- MIS-C is more common in older children (median age 9 years) compared to Kawasaki disease where 80% of patients are below 5 years of age.
- The children developing the syndrome are usually basically healthy.
Symptoms and findings
- A multisystem disease where 90% of patients develop symptoms in four or more organ systems.
- In addition to prolonged high fever, the most common findings include
- abdominal pain
- vomiting
- rash
- diarrhoea
- conjunctival injection.
- Respiratory symptoms are clearly rarer than in COVID-19 infections requiring hospital treatment.
- 80% of patients with the syndrome have cardiovascular findings, such as cardiac failure, shock, pericarditis, myocarditis or changes in coronary arteries.
- It should be noted that half of the patients have hypotension and one in three have symptoms of shock.
- Laboratory findings are consistent with a severe inflammatory reaction.
- Of inflammatory markers, CRP and IL-6, and cardiac enzymes, such as troponin (TnI, TnT) and BNP/proBNP, are considerably elevated.
- In addition, thrombocytopenia and lymphocytopenia are common.
Diagnostic criteria
- WHO criteria for MIS-C (all six must be fulfilled)
- Age 0-19 yrs
- Fever for at least 3 days
- Evidence of a multisystem disease (with at least 2 of the following 5 findings)
- Rash, non-purulent conjunctival injection or muco-cutaneous inflammation signs in hands, feet or oral mucosa
- Hypotension or shock
- Cardiac involvement, such as pericarditis, valvulitis or coronary abnormalities (ultrasound finding or elevated cardiac enzyme levels)
- Coagulopathy (APTT, prothrombin time, D-dimer).
- Gastrointestinal symptoms (diarrhoea, vomiting, abdominal pain)
- Elevated inflammatory markers (CRP, ESR, or procalcitonin)
- No other explanatory infection (such as sepsis, toxic shock syndrome)
- Evidence of SARS-CoV-2 infection (PCR, serology or positive antigen test or contact with a patient with COVID-19)
Workup and treatment
- The children are very sick and always require hospital treatment and investigations. Half of the patients need intensive care.
- All of them need echocardiography and close follow-up of haemodynamics.
- The treatment follows the lines of treatment of Kawasaki disease.
- Patients are given high-dose intravenous immunoglobulin, often with a glucocorticoid.
- In addition, pharmacotherapy is often needed for circulatory support.
Prognosis
- The prognosis is mostly good, and most children recover well.
- Mortality has been 1-2%.
- The long-term consequences of severe disease are unknown, and follow-up studies are needed.
References