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Rare Syndrome Striking Some Kids Who Test Positive for Coronavirus

Warning signs doctors, parents, grandparents and caregivers shouldn't ignore

Grandfather accompanies a small boy at a pediatric exam

Jecapix/Getty Images

En español | The Centers for Disease Control and Prevention (CDC) on Thursday warned physicians to be on the lookout for a rare but serious health condition associated with the coronavirus that has been documented in children throughout Europe and the U.S.

Multisystem inflammatory syndrome in children (MIS-C), as it's known, is described as “a severe inflammatory syndrome with Kawasaki disease–like features.” (Kawasaki disease, an illness that causes inflammation in the walls of some blood vessels in the body, most commonly occurs in children under age 5.) The syndrome, which can cause lasting damage to the heart and other organs, is marked by fever, low blood pressure and elevated inflammatory markers in bloodwork. Most children diagnosed with MIS-C have tested positive for either a current or past coronavirus infection.

So far, cases of MIS-C have been reported only in children, mostly in areas hit hardest by the coronavirus. A study published in The Lancet found that in Italy's Bergamo province, just outside Milan, hospitals documented a 30-fold increase in the incidence of MIS-C in the last month. New York state is investigating more than 100 cases and three deaths linked to the inflammatory syndrome; New Jersey is also reporting a handful of cases.

Since the start of the pandemic, children have been less affected by the coronavirus than adults. Kids with COVID-19, the illness caused by the virus, generally have mild symptoms, if any at all, according to the CDC. And hospitalization rates have remained low.

"But what we've seen across the world, and what people are reporting now, is that sometime after their interaction with COVID these children are developing an inflammatory response throughout their bodies,” says Sara Goza, a pediatrician and president of the American Academy of Pediatrics. Sometimes the illness can pop up even weeks after a coronavirus infection, she adds.

What doctors think is happening is that when children “recover from their initial infection, their body mounts a really abnormal, overexuberant immune response, and that is what really is causing these serious symptoms,” explains Audrey John, chief of the Division of Pediatric Infectious Diseases at Children's Hospital of Philadelphia.

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"We're just now starting to realize that this is happening. And so there's a lot of people looking at it, trying to figure out where it's coming from, what's causing it. And that's true of COVID-19 in adults, too. We still don't know all this virus can do,” Goza says.

Warning signs: When to worry about kids

It's important to keep in mind that while more cases of MIS-C are starting to pop up, it's still relatively uncommon, Goza stresses. “I would caution parents not to panic,” she adds. “The key is if your child is sick, call your pediatrician.”

Here are symptoms that Goza says parents, grandparents and caregivers should be on the lookout for:

  • Persistent fever
  • Serious abdominal pain
  • Trouble breathing
  • A sudden rash
  • An overall ill feeling

"A one-day fever is not unusual in a child, but if it's after a couple days and they're still having super-high fevers,” they need to be examined by a doctor, John says. “I know that a lot of families are worried about going to the doctor in the middle of the pandemic drama, but they should really not hesitate to seek care when they're worried.”

John emphasizes that most children who have come down with the illness respond to treatment and recover. “They're able to leave the [intensive care unit] and their heart function returns to normal. So unlike viral infection with the novel coronavirus, we do have effective treatments that seem to be working in these children,” she says.

It's unclear whether kids with underlying health conditions are at higher risk for developing the syndrome. Based on what we know now, Goza says, “it can happen to anyone.”

"If you notice something different with your child, it doesn't matter; call your pediatrician so you can get checked to make sure that everything is OK,” Goza says. “And if it's not, pediatricians know where to send you to get you the right care at the right time.”