Scientists finally explain MIS-C, the rare post-COVID sydrome seen in kids

Scientists have discovered the trigger that makes inflammation spiral out of control for some children after a COVID-19 infection.

It turns out, the immune system mistakes a protein made in most parts of the body as foreign because it mimics one that forms part of SARS-CoV-2, the virus that causes COVID-19.

The condition, called multisystem inflammatory syndrome in children (MIS-C), was first identified early in the pandemic in a small percentage of children who recovered from COVID-19.

Many of these children were initially asymptomatic during a bout with the viral infection but, two to six weeks later, had life-threatening, runaway iNFLaMMAtion in the heart, brain, skin, blood or digestive system.

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MIS-C always comes with a fever, but it can also cause weakness, dizziness, stomach pain or rash.

Until recently, scientists weren't sure exactly how COVID-19 and MIS-C were linked or why the immune system might turn on the body after an infection. To understand what drives iNFLaMMAtion in MIS-C, researchers profiled the immune systems of 199 children with MIS-C and 45 who recovered without developing the condition.