COVID-19 and Kids: What to Know About Multisystem Inflammatory Syndrome in Children

A NewYork-Presbyterian pediatrician explains how MIS-C works and the symptoms parents should look for.

A young boy with a fever, one symptom of pediatric multi-system inflammatory syndrome.
A young boy with a fever, one symptom of pediatric multi-system inflammatory syndrome.

During the peak of the coronavirus outbreak last spring, doctors at NewYork-Presbyterian Morgan Stanley Children’s Hospital noticed a cluster of about 30 young patients who were being admitted with similar symptoms: high fever, a distinct rash, some swelling.

As New York continued adjusting to a “new normal” amid the COVID-19 pandemic, it turns out another illness was emerging: multisystem inflammatory syndrome in children or MIS-C (formerly referred to as pediatric multi-system inflammatory syndrome or PMIS).

“We thought these cases might have something to do with COVID,” says Dr. Steven Kernie, chief of pediatric critical care medicine at NewYork-Presbyterian Morgan Stanley Children’s Hospital. “But some patients were testing positive for COVID, some were not. It wasn’t until we got a bunch of patients and we were able to conduct antibody testing on all of them that we found out everyone who had these symptoms also had a history of COVID exposure.”

Since then, there have been more than 75 patients at NewYork-Presbyterian Morgan Stanley Children’s Hospital — and 341 total in New York State as of Feb.1 — who have been diagnosed with MIS-C, which affects children ranging from toddlers to teens who have been exposed to COVID-19.

In recent months, as more people grappled with COVID in the face of a pandemic winter and emerging new variants, “not surprisingly we are seeing a few more cases of MIS-C than we saw a few months ago,” says Dr. Kernie. “But it is treatable, and by and large kids do very well.”

Patients who have been admitted at NewYork-Presbyterian Morgan Stanley Children’s Hospital have had symptoms such as a fever, vomiting, lethargy, and abdominal pain, says Dr. Kernie. And while the syndrome is considered rare, it can be serious: Some patients still require treatment in the intensive care unit.

Health Matters talked to Dr. Kernie to learn the latest details about MIS-C and what parents need to look for in their children.

What is an inflammatory syndrome?
An inflammatory syndrome occurs when the immune system becomes overactive. In this case, the body releases cytokines [proteins that help regulate the body’s immune response], which help mediate a high fever. It’s a natural response to infection. But in this case, there seems to be an overreaction to the infection, which happens sometimes after viral infections. As the body is learning to become immune to the virus, the immune system becomes overactive. That’s what we think is going on here.

Dr. Steven Kernie, expert on COVID-19 and pediatric multi-system inflammatory syndrome.

Dr. Steven Kernie

What symptoms should parents be on the lookout for?
This is called a syndrome because it’s not just one symptom. It’s a number of them, and there aren’t exact criteria for this illness because it’s new. What we do know is that there are rarely problems breathing as seen in adults who have COVID. Fever is a main symptom, usually a fever around 102 or 103 degrees that lasts for several days. Abdominal pain and vomiting often occur with a diffuse, red rash that can be everywhere — the inside of the mouth, the inside of eyes, on the palms of hands, on the soles of feet. It’s typically a pretty impressive rash, and there can also be a little swelling. Overall, the kids look sick. In some cases, when kids get a viral infection, they still look pretty healthy. But kids with this syndrome are kind of lethargic, and they don’t want to eat. If your child exhibits a combination of these symptoms, you should contact your pediatrician.

Does a child have to be exposed to COVID-19 in order to develop this illness?
Yes, they do. We don’t diagnose children with this syndrome unless we know they’ve been exposed to COVID. You may not know your child has been exposed because kids have such mild symptoms to primary COVID infection, so we check for antibodies. If the antibody tests are positive, then they’ve been exposed, and this [syndrome] seems to come on several weeks later. It’s probably somewhere between three and six weeks after they were exposed, but we don’t know exactly.

How common is this syndrome?
The good news is we think this is very rare. We believe that many of the children with primary COVID infection never got diagnosed because they are often asymptomatic. In the New York City area alone, that’s probably hundreds of thousands of kids, so very few patients are developing the symptoms for this new syndrome in comparison to the number of kids who were probably exposed to primary COVID infection.

What’s the relationship between MIS-C and Kawasaki disease and toxic shock syndrome?
Only that it looks like some of the features of Kawasaki disease. The red eyes, high fever, and sometimes cracked lips, those are typical signs of Kawasaki. We know with Kawasaki disease, children can get coronary artery aneurysms, which is the real worry, and we have rarely seen this in the patients we have treated. So, we are unsure how that condition may be a part of this.

However, with this syndrome, a child’s body can go into shock, which is defined by a high heart rate and low blood pressure. It’s when the heart can’t keep up with the metabolic demands of the body. But I don’t know why people have been referring to toxic shock syndrome. That’s when there’s a release of a toxin that activates cytokine release due to infection with certain bacteria. That’s not what we believe happens here, but some of the symptoms are similar, such as the low blood pressure and the rash.

“The reassuring thing is, No. 1: This is rare. ”

— Dr. Steven Kernie

What’s the treatment for multisystem inflammatory syndrome in children?
There is a spectrum — we’ve got mild, moderate, and severe categories. We think, in general, it’s self-limited, meaning the body will figure everything out and tones down the immune response. But if a child is very sick, they need treatment, which involves immunosuppression and things to suppress the immune system, such as steroids and immunoglobulin therapy. The other thing that we will give sometimes are immunomodulators to help tamp down the overactive immune system. Overall, treatment could be a few days to over a week. What we’re not seeing are kids who need to be put on ventilators or having prolonged stays at the hospital.

Is there an isolation period for the children after they recover?
MIS-C is a separate illness from the primary COVID-19 infection and is not contagious. But a child with this syndrome could still have an active COVID-19 infection and therefore be contagious. By the time they get this syndrome, more than half the kids, fortunately, don’t have evidence of an active COVID-19 infection. So once they’re recovered, we don’t believe they’re contagious.

Can a child infect siblings or parents with this illness?
We haven’t seen siblings coming in with it, and you would expect that siblings would have been exposed around the same time. But it just seems to be affecting kids in a random way. We haven’t seen this syndrome in adults, which is not surprising because we think part of the reason it occurs in kids is because their immune systems are just less mature. For some reason, some kids have a more active immune response to COVID, and, as far as I know, this hasn’t really been noted in adults.

What can you tell parents to ease anxiety about this new syndrome?
The reassuring thing is, No. 1: This is rare. We really think very few children who have been exposed to COVID will develop this. No. 2: It’s treatable. We have good treatments for it, and we’re seeing kids respond very well so far. No. 3: If your child does happen to have it, it’s not subtle. Your child will look sick. It’s not the case where a child will be completely fine one moment and then have this overwhelming case of specific inflammatory syndrome the next. It takes a little while to develop, and you will notice a marked difference in the way your child behaves and feels.

What’s next as we learn more about this emerging illness?
We don’t know exactly how it’s going to evolve. At NewYork-Presbyterian Morgan Stanley Children’s Hospital we are conducting NIH and industry-funded research on MIS-C in order to try and understand it better. All children diagnosed here are also followed up for at least six months in order to determine if there are more long-term effects of having MIS-C. So far those studies are encouraging and suggest that they are not. We don’t seem to be getting overwhelmed with patients with this syndrome, so we don’t expect a huge spike in cases. But we’re preparing for everything. We’re also doing lots of testing to see why these patients’ immune systems are overly active. But the good news is that, right now, most kids don’t seem to have this condition.

Steven Kernie, M.D., is chief of pediatric critical care medicine at NewYork-Presbyterian Morgan Stanley Children’s Hospital. He is also a professor of pediatrics and vice chair for clinical affairs at Columbia University Vagelos College of Physicians and Surgeons.

At A Glance


Consult an Expert

Find a Doctor or call