What is Multisystem Inflammatory Syndrome in Children (MIS-C), and when should parents seek help?

Multisystem Inflammatory Syndrome in Children, or MIS-C, is a new pediatric disease caused by an abnormal immune reaction to COVID-19. Children with MIS-C are not suffering from direct effects of the viral infections – rather they are experiencing effects from their own inflammation system being triggered by the virus.

Researchers are still learning about MIS-C, but have discovered that it behaves similarly to Kawasaki disease.

Mary Bridge Children’s Infectious Diseases physician, Mary Fairchok, MD, says there are common symptoms parents should watch for. “Parental instinct is rarely wrong,” Dr. Fairchok said. “If your child isn’t looking or acting like themselves with even one day of fever, or has an unexplained high fever lasting more than three days, definitely contact their primary care provider right away.”

What are the symptoms of MIS-C?
A high fever that lasts for three or more days is the most common symptom, but other symptoms must also be present and can include:

· Dizziness

· Seizures

· Rashes

· Vomiting

· Severe abdominal pain, resembling appendicitis

· Red eyes or lips

Many children have mild to moderate cases and require minimal or no hospital support. However, in more severe cases, aggressive treatment is required because the disease can quickly rage out of control. The inflammation set off can wreak havoc on multiple organs and systems, especially the heart, and some children will require intensive care. Dr. Fairchok noted that although we are still learning the best treatment protocols, we do have treatments that have been very effective in turning off the inflammation.

MIS-C doesn’t always require a trip to the Emergency Department, but you should seek emergency care immediately if your child shows alarming or unexplained symptoms like the ones listed above.

It’s still too early to know what long-term impacts the disease will have on these children. They require careful monitoring by the infectious diseases team as well as cardiologists for at least six weeks after recovery. Dr. Fairchok says MIS-C is something we’ll likely see for quite a while, as it appears weeks to months after the infection with COVID-19, so cases will continue to appear even after infection rates have declined.

How common is MIS-C and is it contagious?
MIS-C was first discovered in the UK last spring. Doctors at Mary Bridge Children’s have seen an increase in cases and have treated more than two dozen patients since May 2020. The disease can affect patients of all ages and ethnicities, but trends show it is more common in Hispanic and Black patient populations.

The uptick in cases is believed to be largely due to the nature of the disease. MIS-C is an unfortunate and consequential immune response to COVID-19, and can show up at the end of a COVID-19 diagnosis or, more commonly, not until quite a while after.

“That’s part of what makes diagnosing MIS-C tricky, because most children are asymptomatic to COVID-19 or tested negative for it, so many parents won’t necessarily know that their child ever even had the virus,” Dr. Fairchok said.

Not all children who contract COVID-19 will also get MIS-C, but to meet the case definition of MIS-C, children must have – at one point – been positive for COVID-19 or have the antibodies to the virus, or close contact with a known case. Parents should also be aware that MIS-C is not contagious and won’t spread to siblings; and by the time it’s identified, it’s usually beyond the window of time for any transmission of COVID-19.