Everything We Know About the Mysterious Childhood Illness Linked to Coronavirus

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In May, doctors in New York watched in alarm as a small but growing number of children were admitted to hospitals with a mysterious illness causing a high fever and rash. The Centers for Disease Control and Prevention has named the illness, which looks similar to Kawasaki disease: multisystem inflammatory syndrome, or MIS-C. While many questions remain, doctors believe that it is linked to the coronavirus, as many of the sick children have tested positive for COVID-19 or its antibodies. Here’s everything we know.

More than 300 children have fallen ill with multisystem inflammatory syndrome.

The most common symptom of multisystem inflammatory syndrome is a temperature of 100.4 degrees Fahrenheit or higher that lasts for several days, according to the New York City Health Department. However, children with the syndrome have exhibited a number of other symptoms, including irritability, abdominal pain, diarrhea, vomiting, rash, red or pink eyes, an enlarged lymph node on one side of the neck, red lips or tongue, and swollen hands and feet, which may also be red.

According to data reported by the CDC, there have been at least 342 cases of MIS-C, and six children with the syndrome have died. While the illness has affected people as old at 20, the majority of reported cases are in children between the ages of 1 and 14 years. Cases have spanned the country, affecting children in 36 states and Washington, D.C., with a majority concentrated in Massachusetts, New York, and New Jersey.

As with the coronavirus, MIS-C has had a disproportionate impact on communities of color. Per the CDC, around 70 percent of cases have occurred in children who are Latinx or non-Hispanic Black, despite the fact that the U.S. child population is approximately 25 percent Hispanic and just over 13 percent non-Hispanic Black.

The illness is linked to the coronavirus.

While the CDC has not explicitly said that the coronavirus causes MIS-C, there’s a clear link between the illnesses. Per the agency, 96 percent of children with the syndrome have tested positive for SARS CoV-2, the virus that causes the coronavirus. (The remaining 4 percent had been in close contact with someone with the coronavirus.) Doctors believe the syndrome may be “a postinfection disease,” where the body’s immune system overreacts in the wake of infection — sometimes as late as four to six weeks after exposure to the coronavirus.

MIS-C is rare but serious.

While the illness appears to be rare, medical experts have stressed the importance of seeking urgent medical care if symptoms occur. James Schneider, a pediatric critical care doctor at Northwell Health, told the Washington Post that patients he’s seen with the syndrome have required blood-pressure medications, steroids, anticoagulants, immunoglobulin — and in rare cases, ventilators.

“So far, from what we understand, this is a rare complication in the pediatric population that they believe is related to COVID-19,” New York State health commissioner Howard Zucker told the New York Times in May. “We are following it very closely.”

This post has been updated.

What We Know About the Childhood Illness Linked to COVID-19