Multisystem inflammatory syndrome in children (MIS-C)

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Multisystem inflammatory syndrome in children (MIS-C) is a syndrome linked to a SARS-CoV-2 infection, the virus responsible for COVID-19.

Key points

MIS-C is a rare but potentially serious illness that can cause a variety of symptoms as a result of inflammation of multiple organs.
MIS-C usually develops several weeks after a SARS-CoV-2 infection.
MIS-C is treatable using medications to control inflammation and to help prevent organ damage.
Most children with MIS-C recover completely with timely medical care.

Introduction

What is multisystem inflammatory syndrome

Multisystem inflammatory syndrome in children (MIS-C), also known as paediatric inflammatory multisystem syndrome (PIMS), is a rare syndrome seen in children about 3 to 6 weeks after they have been exposed to SARS-CoV-2, the virus responsible for COVID-19. Most children who are infected with SARS-CoV-2 will not develop MIS-C. In some children, SARS-CoV-2 may cause a delayed immune response leading to fever and inflammation of any organ including the heart and blood vessels, kidneys, digestive system, lungs, brain, skin and eyes weeks after they have had a SARS-CoV-2 infection.

MIS-C is similar to Kawasaki disease as well as toxic shock syndrome (a bacterial infection), but a clear connection has not been confirmed.

Signs and symptoms

Signs and symptoms of MIS-C

Children with MIS-C have fevers that have no known cause and are difficult to treat. They will also have different signs and symptoms depending on which body parts are affected. Children with MIS-C can have some or all of the signs and symptoms. These can include:

rash
red eyes
cracked lips and/or red (strawberry-like) tongue
swollen lymph nodes in the neck
swollen and/or red hands and feet
stomach pain, diarrhea and/or vomiting
difficulty breathing
fatigue or lethargy
headache, irritability and/or confusion

Causes, risk factors and prevalence

Cause of MIS-C

The exact cause of MIS-C is unknown, but it has been linked to SARS-CoV-2. It is not known if some children are more likely to develop MIS-C. Many children with MIS-C may test negative for a SARS-CoV2 infection and they may not have a history of symptoms consistent with the virus.

MIS-C is rare. Most affected children do not have underlying health conditions. This syndrome can affect children of all age groups and ethnic backgrounds. However, older children and children of Afro-Caribbean, Hispanic and South Asian descent seem to be at greater risk of developing MIS-C.

Diagnosis

How MIS-C is diagnosed

There is no specific test to diagnose MIS-C. The diagnosis is based on a combination of history, physical exam and lab tests that look for signs of inflammation if there is no other diagnosis.

If a diagnosis of MIS-C is suspected, your child will likely be admitted to hospital to be closely watched and to have blood tests to monitor the level of inflammation. Some children may require treatment. Most children are discharged home after a few days.

MIS-C is not contagious and cannot spread from one person to another.

Treatment

Treatment of MIS-C

Some children may require treatment in the form of medication. There are several ways to treat MIS-C. The focus of treatment is to reduce inflammation using intravenous immunoglobulin (IVIG) and/or corticosteroids and potentially other medicines that suppress the immune system. Another frequently used medication is ASA (acetylsalicylic acid or Aspirin) which helps prevent your child’s blood platelets from sticking together. ASA should only be given to children under the direction of a doctor.

Prevention

Can MIS-C be prevented?

There is no known way to prevent MIS-C but you should continue to follow public health guidelines to reduce the risk of exposure to COVID-19 including the use of masks, hand hygiene and vaccination.

Complications

Complications of MIS-C

Although rare, some children may become ill quickly because of inflammation in the intestines, brain, kidneys or heart. Like Kawasaki disease, the blood vessels of the heart (coronary arteries) and the heart itself may become inflamed.

Helping your child

Caring for your child with MIS-C at home

Most children recover quickly and can go home from the hospital after a few days. Your child may need to continue taking medications at home such as aspirin and/or corticosteroids. At a follow-up visit, the specialists will advise you when to stop these medications. Once your child has the energy to participate in activities, and no longer has any fever or pain, you may send your child back to school. You should talk to your doctor at your follow-up visit about this.

Follow-up care

Follow-up care for MIS-C

Children diagnosed with MIS-C need follow-up in a multidisciplinary clinic where they will have repeat bloodwork, monitoring of their heart and assessment by a specialized team. You will be given a date for your child’s follow-up appointment either when they are discharged from the hospital or soon after.

When to seek medical attention

When to see a health-care provider

Contact your child’s health-care provider if your child has a persistent fever and symptoms that could be MIS-C.

Take your child to an Emergency Department if your child has any of the following warning signs:

Change in behaviour, with poor energy, weakness or fussiness despite good fever control
Difficulty waking up or is not interacting
Not drinking or has repeated vomiting
Very fast heart rate even when the fever is down
Difficult, fast or noisy breathing
Blue lips or mottled skin
Seizure or convulsion
Combination of red eyes, red lips and red rash

Your child may show physical changes when their condition is serious or when their condition gets worse. Parents and caregivers can learn how to spot these signs in order to seek help from a health-care provider.

Resources

Centers for Disease Control and Prevention (CDC) guidance on MIS-C
https://www.cdc.gov/coronavirus/2019-ncov/daily-life-coping/children/mis-c.html

Canadian Pediatric Society Public Health Alert
https://www.cpsp.cps.ca/uploads/private/CPSP_Public_Health_Alert_Acute_inflammatory_illn ess_and_COVID-19.pdf

World health organization scientific brief on multisystem inflammatory syndrome in children and adolescents with COVID-19
https://www.who.int/publications-detail/multisystem-inflammatory-syndrome-in-children-andadolescents-with-covid-19

References

Henderson, L.A., Canna, S.W., Friedman, K.G., Gorelik, M., Lapidus, S.K., Bassiri, H., Behrens, E.M., Ferris, A., Kernan, K.F., Schulert, G.S., Seo, P., F. Son, M.B., Tremoulet, A.H., Yeung, R.S.M., Mudano, A.S., Turner, A.S., Karp, D.R., & Mehta, J.J. (2020). American College of Rheumatology Clinical Guidance for Multisystem Inflammatory Syndrome in Children Associated With SARS–CoV‐2 and Hyperinflammation in Pediatric COVID‐19: Version 1. Arthritis & Rheumatology, 72: 1791-1805. https://doi.org/10.1002/art.41454

Jiang, L., Tang, K., Levin, M., Irfan, O., Morris, S.K., Wilson, K., Klein, J.D., & Bhutta, Z.A. (2020). COVID-19 and multisystem inflammatory syndrome in children and adolescents. The Lancet. Infectious diseases. 20(11), e276-e288. https://doi.org/10.1016/S1473-3099(20)30651-4

Tam, H., El Tal, T., Go, E., & Yeung, R.S.M. (2020). Pediatric inflammatory multisystem syndrome temporally associated with COVID-19: a spectrum of diseases with many names. Canadian Medical Association Journal. 192(38), E1093-E1096. https://doi.org/10.1503/cmaj.201600

Last updated: December 6th 2023