Multisystem Inflammatory Syndrome in Children (MIS-C) Associated with COVID-19

When the COVID-19 crisis began, many parents were relieved to hear the virus did not appear to impact children to the same extent as other populations as most children with a positive COVID-19 status exhibit mild symptoms or no symptoms at all. However, as the virus has progressed, some children are experiencing symptoms similar to a rare pediatric illness called Kawasaki disease in addition to other signs of inflammation about a month after they have been exposed to the coronavirus.

At Mass General Hospital for Children, a multidisciplinary group—including Joanne Chiu, MD, and Manuella Lahoud-Rahme, MD, both of whom specialize in pediatric cardiology, and Ann Murray, MD, MPH, pediatric infectious disease specialist, primary care pediatrician and medical educator—came together to understand this illness and raise awareness among pediatricians. Below, they explain the links between MIS-C and COVID-19 in children.

Links between MIS-C and COVID-19 in children

MIS-C is a presentation in children with inflammatory symptoms, some of which may appear similar to symptoms of Kawasaki disease. Kawasaki disease is a rare, but serious illness in children that causes inflammation of blood vessels, also known as medium-sized vasculitis.

"Unfortunately, although it has been studied for decades, the cause of classical Kawasaki disease is not known," says Dr. Murray.

She suggests that Kawasaki disease is possibly an immune response related to a virus, as there are often outbreaks amongst patients during the winter and spring following recovery from a viral infection.

"What we know about this MIS-C is that it is a reaction of the auto-immune system to the virus," says Dr. Lahoud-Rahme.

New York City and Italy have reported that a month after the community's peak infection rate, some children are getting sick with hyperinflammatory symptoms. Researchers are in the early stages of collecting data about this illness.

Much like in classic Kawasaki disease, the coronavirus may be causing the immune system to overreact and attack its own cells.

Dr. Murray says, "I suspect the virus is triggering an abnormal and extremely exaggerated immune response with a cytokine storm."

Kawasaki-Like Symptoms in Children with COVID-19

Similarities to classic Kawasaki disease include persistent fever and inflammatory markers such as redness, swelling and rash. There are several key differences in MIS-C, such as:

• Affects older children (ages 5 and above)
• Causes more inflammation
• Results in more problems with blood pressure and cardiac function
• Indicates a higher risk of severe presentation

Watch for These Symptoms

"I don't want  parents to worry that this is something inevitable and that is going to happen if their child has an infection," says Dr. Chiu. "It is still very rare. Do not worry unless your child is showing symptoms."

When children experience the symptoms, their sickness may escalate very quickly and they may require medical treatment. Call your child's pediatrician right away if you notice any of these symptoms:

1. Fever for at least 24 hours
2. Low energy (sleepiness, lethargy, not walking around)
3. Tummy troubles (abdominal pain, lack of appetite, diarrhea)
4. Any Kawasaki-like symptoms (redness, swelling, rash)

If Kids are Exposed to Coronavirus, Will They Get Sick?

Most children who are exposed to coronavirus are asymptomatic or have very mild symptoms. Early data from Italy shows 1 in 1,000 kids experience Kawasaki-like symptoms. Reports of 160 sick children from New York may sound scary, but when you put that number into the context of 1.7 million children living in the city with 10,000 known positive pediatric cases in the state, it is clear that a very small percentage of children who are exposed to coronavirus experience this illness.

"Even if they do get sick, most of the children do improve," Dr. Chiu says. She explains that treatment includes supportive care and medication such as steroids and immunoglobulin to control inflammation and lower the risk of aneurysms in the cardiac arteries.

"Even in these most severe presentations," says Dr. Murray, "most children have a relatively short hospital stay and are going home and recovering in a short timeframe, which is quite a stark difference from the horrible disease that this virus is causing in the adult population with prolonged hospitalizations and high mortality."