Multisystem Inflammatory Syndrome in Children (MIS-C)


MIS-C is caused by an abnormal immune system’s response to COVID-19 exposure. After exposure to COVID-19, the immune system in a small percentage of children can sometimes produce an exaggerated response to virus. This abnormal inflammatory response results in the features of the disease and may cause injury to one or more organs.

What Are the Signs/Symptoms?

Over 90% of COVID 19 infections in children are asymptomatic. The most common symptoms are cough, fever, diarrhea, and vomiting. Infants under 12 months of age may have poor appetite and feeding issues. MIS-C has similar findings but is complication of COVID-19 infection and can resemble other rheumatological disorders such as macrophage activation syndrome, systemic vasculitis, and Kawasaki disease. Having confirmed COVID-19 positivity helps with making the diagnosis. The most concerning manifestations are heart inflammation and failure, severely low blood pressure, an abnormal blood cell count that can further damage other organs like the kidneys or brain.

What Are Common Treatments?

Most children with MIS-C are treated in the hospital. As patients may present with low blood pressure and cell counts, fluids and antibiotics are often administered until an active infection can be ruled out. Most patients with MIS-C are treated with drugs that regulate the immune system including steroids and IVIG (intravenous immunoglobulin) to dampen its response. For patients who do not improve, addition of infliximab (a tumor necrosis factor [TNF] inhibitor), or anakinra (an interleukin-1 [IL-1]) inhibitor) can be added. Due to the increased risk for blood clots in patients with MIS-C, patients are also treated with low-dose aspirin. The child’s symptoms and the severity of illness will determine which treatments are needed.

Living with MIS-C

With prompt diagnosis and proper treatment, most children will make a full recovery from MIS-C. At discharge, patients with MIS-C are closely monitored on an outpatient basis by pediatric specialists in rheumatology, infectious disease, and hematology. In cases where there is heart involvement, particularly close follow-up with a pediatric cardiologist is required.

MIS-C is a multi-system, multi-organ illness that requires the expertise of multiple specialists. Pediatric rheumatologists assist in the diagnosis of MIS-C and may aid in the dosing and administration of immunomodulatory medications.

Updated February 2023 by David Waldburg, MD, and reviewed by the American College of Rheumatology Committee on Communications and Marketing.

This information is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis and treatment of a medical or health condition.

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