What's the Difference Between MIS-C, Kawasaki Disease, and Severe COVID-19?

Hospital Assessment

Key Takeaways

  • Severe COVID-19 is more common in children with underlying medical conditions.
  • MIS-C is more common after an asymptomatic-mild case of COVID-19.
  • Kawasaki has similar symptoms to MIS-C but is not confirmed to be related to COVID-19.

A recent study published in the Journal of the American Medical Association has revealed the key clinical differences between severe COVID-19 (requiring hospitalization) and multisystem inflammatory syndrome in children (MIS-C).

The study reviewed clinical information from 1,116 children and adolescents over an eight-month period across 66 U.S. medical facilities to help the medical community better understand the differences in symptoms, clinical picture, and outcomes of these conditions. 

Adrienne Randolph, MD, MSc, professor of pediatrics and anesthesia at Harvard Medical School and Boston Children's Hospital, headed the Overcoming COVID-19 Network that conducted the study. She helps break down the differences between these two conditions, as well as Kawasaki disease, which often presents similarly to MIS-C.

She reassures parents that even though these conditions can seem scary, the risk of children contracting any of these is very low. For most children who do contract COVID-19, their cases will be mild. "The great majority of kids have mild to asymptomatic involvement with COVID," she says.


The following outlines what the aforementioned study found most commonly. It is important to understand that there is the potential that all children, of all ages and backgrounds, may experience any of these conditions. If you are concerned that your child is unwell, it is important that you speak to your pediatrician promptly.

Severe COVID-19

Severe COVID-19 generally occurs in the acute (initial) phase of infection with the SARS-CoV-2 virus. Severe COVID-19 is contagious.

How does it affect the body? Most children will have difficulty with their breathing. Some children may have difficulties with other body systems as well as or instead of breathing difficulties. Other body organs that might be affected include the heart, brain, kidneys, blood, or gastrointestinal system (digestion). 

Adrienne Randolph, MD, MSc

The great majority of kids have mild to asymptomatic involvement with COVID-19.

— Adrienne Randolph, MD, MSc

What care do they require? Children with severe COVID-19 sometimes require intensive care, but most cases are able to be cared for in a hospital ward-based environment. 

What are the common symptoms? Fever, fatigue, muscle aches/joint pains, cough, difficulty breathing, pain in the chest.

How long will it take to recover? This is individual and will depend on the severity of the condition.

Who is most at risk? Children aged under the age of 5 or older than 13 with underlying medical conditions are more often affected by severe COVID-19. 

How is it diagnosed? PCR test (respiratory test). 

Multisystem Inflammatory Syndrome in Children (MIS-C)

MIS-C commonly occurs three to six weeks after a mild or asymptomatic case of COVID-19 or an exposure to someone who has had COVID-19. MIS-C is not contagious. 

How does it affect the body? Children will have very high levels of inflammation throughout the body. At least two or more body systems will be involved and the lungs, heart, brain, kidneys, blood, skin, or gastrointestinal system (digestion) may be affected. About half of all children with MIS-C experience cardiac complications which inhibit the heart from pumping blood and oxygen effectively around the body. They may also have dilated blood vessels (aneurysms) surrounding the heart.

Adrienne Randolph, MD, MSc

Most of the kids with MIS-C went to the ICU to get care, whereas in Kawasaki Disease [most] of them were on the ward. They don't necessarily need intensive care most of the time.

— Adrienne Randolph, MD, MSc

What care do they require? Children with MIS-C usually require admission to a pediatric intensive care unit.

What are the common symptoms? Children with MIS-C usually have persistent high fevers that last for 3 or more days. They also commonly have headaches, gastrointestinal upset (stomach pain, vomiting, diarrhea), and mucocutaneous symptoms that can include rashes, conjunctivitis, sores in and around the mouth and lips, and peeling of the hands and feet. These children typically look and feel very unwell. 

How long will it take to recover? Most children with MIS-C recover in approximately 30 days with treatment. 

Who is most at risk? Children with MIS-C are most commonly aged 6-12 years of age with no underlying medical illness who have experienced a mild or asymptomatic case of COVID-19. Black, non-Hispanic children tend to experience MIS-C more than other children. The reason for this is still unknown.

How is it diagnosed? Children must have elevated inflammatory markers in numerous blood tests, have been exposed to COVID-19, and have no other explanation for their illness (such as a bacterial infection). They must also be exhibiting symptoms consistent with the illness and be aged under 21 years. 

Children who have recovered from MIS-C should make sure to stay on top of their COVID vaccinations. Research published in January 2023 showed patients with a history of MIS-C had no adverse reactions to the vaccine. One caveat—if your child has had MIS-C, they should wait 90 days after diagnosis to receive the vaccine.

Kawasaki Disease (Kawasaki Syndrome)

Kawasaki disease is an illness that has no known cause. It is suspected that exposure to a virus (not necessarily SARS-CoV-2) may trigger the condition, but this has not been confirmed. Kawasaki disease is not contagious.

How does it affect the body? Kawasaki disease causes high levels of inflammation in the blood vessels. This can lead to aneurysms (dilation) in the blood vessels around the heart and subsequent cardiac conditions in some children.

What care do they require? Initial investigations and treatment are required in the hospital ward setting and may take several days. Care can continue at home after that. 

What are common symptoms? Persistent fevers lasting 5 or more days, mucocutaneous symptoms that can include rashes, conjunctivitis, sores in and around the mouth and lips, gastrointestinal upset (stomach pain, vomiting, diarrhea). Children may also have a red swollen appearance to the tongue, palms of the hands, and soles of the feet.

How long will it take to recover? This depends on the severity and how quickly treatment is sought. Once treatment begins in the hospital, symptoms can resolve in as little as 24 hours. Children will take longer to fully recover and may feel fatigued for some weeks after their initial diagnosis. All children who have experienced Kawasaki disease should have ongoing cardiac reviews for life.

Who is most at risk? This disorder is usually diagnosed in children under the age of 5 years, however can affect older children also. Boys are more prone to the disease than girls and it is seen more often in Asian and Pacific Islander children. 

How is it diagnosed? Kawasaki is diagnosed by symptoms, clinical signs, blood tests, and the absence of any other explanation.

Is It Safe for My Child to Go to School? 

The risk of your child developing complications from a case of COVID-19 is very small. What is a greater risk right now is the epidemic of mental health concerns in children due to social isolation. 

“Right now we have a new epidemic of mental health crises from all these kids not being able to have social interactions that are normal and it's been going on for a year,” explains Randolph. 

She reminds parents that with safety measures in place (masking, hand washing, physical distancing) it is generally safe for you to send your child to school and it is important to do so for their mental health. 

“We want to continue to wear the masks and be safe,” says Randolph, “but these [conditions] are still rare complications compared to some of the more common complications that are part of the pandemic [especially] the psychological stress on children.”

Is It Safe for My Child to Get the Vaccination? 

Because testing is still underway in the pediatric community, it is not yet known if pediatric vaccinations will trigger complications associated with COVID-19. However, Randolph reports that in populations aged 16 and over there have been no reported cases of MIS-A (multisystem inflammatory syndrome - adult) or MIS-C from COVID-19 vaccination. 

“The risk of acute COVID-19 complications hopefully will be reduced with getting [the] vaccination and ... we're going to be monitoring this with the CDC, looking at vaccinated versus not vaccinated children who present with MIS-C,” explains Randolph. “We're going to be doing a year-long study looking at that as our next phase and it's likely vaccination, in general, prevents complications.”

What This Means for You

Knowledge is key when it comes to protecting your child during a pandemic, and having a firm understanding of COVID-19-adjacent illnesses like MIS-C and Kawasaki disease will help you stay aware of developing symptoms.

Still, remember to always seek out a COVID-19 test before making any assumptions about your child's condition, and talk to their pediatrician when seeking treatment.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

5 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Feldstein LR, Tenforde MW, Friedman KG, et al. Characteristics and outcomes of US children and adolescents with multisystem inflammatory syndrome in children (MIS-C) compared with severe acute COVID-19JAMA. 2021;325(11):1074-1087. doi:10.1001/jama.2021.2091

  2. Centers for Disease Control and Prevention. COVID-19 in children and teens.

  3. Elias MD, Truong DT, Oster ME, et al. Examination of adverse reactions after covid-19 vaccination among patients with a history of multisystem inflammatory syndrome in children. JAMA Netw Open. 2023;6(1):e2248987. doi:10.1001/jamanetworkopen.2022.48987

  4. Kawasaki Disease Foundation. What is Kawasaki disease?

  5. Kawasaki Disease Foundation. Kawasaki disease: a parents guide. YouTube.

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