Here’s What Parents Need to Know About Kawasaki Disease, Multisystem Inflammatory Syndrome, and COVID-19

A rare illness is landing kids in the hospital — and it's probably related to COVID-19. But don't freak out.

Over the past year, more than 2,000 children in the U.S. have been diagnosed with a strange syndrome associated with COVID-19. Experts are on the lookout for more cases to try to understand why some kids are getting it and how it’s related to the coronavirus. The illness appears similar to toxic shock syndrome and Kawasaki disease, a rare but serious childhood heart condition. However, it doesn’t perfectly line up with either. Experts previously called this new disease pediatric multisystem inflammatory syndrome (PMIS), but they now refer to it as multisystem inflammatory syndrome in children (MIS-C). At least one prominent doctor suspects that it’s not a mysterious pediatric disease at all, but a normal effect of COVID-19 commonly seen in adult patients.

Kids with the illness often have a fever, rash, abdominal pain, or vomiting. The disease can be painful, feeling like “someone injected you with straight-up fire,” one teen who has recovered from it told the New York Times. And since the beginning of the pandemic, cases of MIS-C have gotten more severe. If your child has these symptoms, call your pediatrician immediately — because early treatment is key. For the rest of us, luckily, this illness seems rare. Not many kids are getting sick with it, just like few get severely ill with COVID-19. But studies suggest it’s more common than experts originally suspected. Here’s what you need to know.

What Does Kawasaki Disease Look Like?

Kawasaki disease is a condition that causes inflammation in the walls of arteries throughout the body. It mostly affects Asian children under the age of 5, though teens and kids of any race can get it too. In addition to fever and rash, kids with the illness may also have bloodshot eyes and swollen hands, feet, mouth, lips, and throat. Kawasaki disease is not contagious, but doctors don’t know what causes it, though they suspect viruses could be one cause. It can damage blood vessels and the heart itself, and even cause a heart attack if not treated promptly, according to the American Heart Association.

What Does Multisystem Inflammatory Syndrome Look Like?

The symptoms of the new syndrome don’t entirely match up with Kawasaki disease, and they also overlap with toxic shock syndrome, which is usually related to bacterial infection and can involve abdominal issues. Unlike COVID-19, multisystem inflammatory syndrome doesn’t attack the lungs and instead causes inflammation throughout the body. Children with the syndrome may have fever, chills, rash, stomach pain, nausea, vomiting, or diarrhea. They may also have neurological symptoms such as headache and confusion, muscle or joint pain, and respiratory symptoms such as congestion, sore throat, cough, shortness of breath, or wheezing, according to a study of 99 kids in New York with the condition. Some also develop red or pink eyes, swollen hands and feet, and red, cracked lips or a red, bumpy tongue like a strawberry, according to a New York health department fact sheet. They may also have inflammation of the heart and other heart complications.

The condition can ultimately cause organ damage and even lead to death. About 80 percent of kids with the syndrome need intensive medical care, 20 percent need a ventilator, and 2 percent die, according to a study from June of 186 patients across 26 states. Several young adults in their 20’s have also been diagnosed with the condition, but the average age of those who do is 8, according to the study. A similar condition, called multisystem inflammatory syndrome in adults (MIS-A) has been reported in a small number of adults up to age 50.

Worryingly, MIS-C appears to be more dangerous now than it was at the start of the pandemic. “We’re now getting more of these MIS-C kids, but this time, it just seems that a higher percentage of them are really critically ill,” Roberta DeBiasi, chief of infectious diseases at Children’s National Hospital in Washington, D.C., told the New York Times. About half of the patients she saw in the first wave needed treatment in an intensive care unit. Now that number is closer to 80 or 90 percent.

How Rare Is It?

Between the U.S. and Puerto Rico, 2,060 children have been diagnosed with MIS-C, and 30 of those kids have died from the condition. More than 3 million children in the US have been diagnosed with COVID-19. For comparison, Kawasaki disease is a winter and spring seasonal disease that impacts about 5,000 kids each year in the United States.

“We want to reassure parents – this appears to be uncommon,” said Jane Newburger, a cardiologist at Boston Children’s Hospital, in a press release from the American Heart Association in May. But the focus on severe cases and narrow definition of what counts as multisystem inflammatory syndrome – a child must have had or been exposed to COVID-19 to be diagnosed – may mean that many cases go unreported, according to an editorial by Michael Levin, a professor of infectious disease and chair of pediatrics and international child health at Imperial College London. “There is concern that children meeting current diagnostic criteria for MIS-C are the “tip of the iceberg,” and a bigger problem may be lurking below the waterline,” he wrote.

Is Multisystem Inflammatory Syndrome Related to COVID-19?

The new condition is related to COVID-19, according to the CDC, but the exact cause of MIS-C is unknown. The CDC and World Health Organization even include having had COVID-19 or having been exposed to it in the definition of the syndrome. Most children with the syndrome either tested positive for the coronavirus or for antibodies (meaning they had previously been infected), according to an advisory from the New York Department of Health. The inflammatory syndrome can occur “days to weeks” after a child has COVID-19, the advisory adds. It could be a “post-infection inflammatory response” in which the body’s immune system overreacts to the coronavirus, doctors told The Guardian.

One prominent doctor suspects that the syndrome isn’t a strange reaction to the coronavirus in kids, but instead a normal effect of COVID-19 that happens in adults too. When reports of the syndrome first came out, physician Sharon Ostfeld-Johns was scared for her child’s life. However, that feeling quickly passed. “The more I read, the less mystery I saw. As I cared for more patients with Covid-19, the number growing into the hundreds, it became clear to me that this wasn’t new,” according to an op-ed in STAT by Ostfeld-Johns, who is also a professor of clinical pediatrics at the Yale University School of Medicine. “It was Covid-19, the same disease I was treating in my adult patients.”

COVID-19 consists of two phases, she writes. First is the viral phase, in which symptoms may or may not appear after infection. The inflammatory phase occurs days to weeks later and can be much more dangerous. The symptoms of her adult patients in this phase vary widely, but they match up perfectly with the symptoms of MIS-C. Some of the symptoms are more prevalent in children, but it’s still the same disease, Ostfeld-Johns writes. The inflammatory condition is probably due to an “overproduction of infection-fighting proteins,” also known as a cytokine storm, she adds.

What is the Treatment for MIS-C?

The good news is that treatment for the inflammatory syndrome is usually effective. The focus of treatment is suppressing the immune system. Doctors do this by giving the children steroids and antibodies purified from donated blood, called immunoglobulin therapy, while in the hospital or an intensive care unit. This treatment helps children’s hearts recover in the majority of cases, according to a study looking back at treatment of 35 kids. Doctors may provide additional care to address other symptoms. Treatment can take anywhere from a few days to more than a week, according to Health Matters by NewYork-Presbyterian Hospital.

COVID-19 isn’t a normal disease. It causes oddball symptoms, such as loss of taste and smell. It likely leads to COVID toes, a toe discoloration that may be a sign of COVID-19 in kids without other hallmarks of the disease. Kawasaki and toxic shock symptoms are next in the long list of unexpected issues. It’s impossible to predict what strange complications are ahead, so stay vigilant. Keep an eye out for funky symptoms in your kid.