As the name implies, MIS-C affects children and adolescents under 21 years old. Most kids and teens diagnosed with MIS-C had mild symptoms of COVID-19 or were asymptomatic, meaning they had no symptoms at all.
Black and Hispanic children have been disproportionally impacted by MIS-C. This could be because people in these groups may be at greater risk of being exposed to COVID-19 or that they have a genetic predisposition. We are still learning about MIS-C and how it affects kids, so we don’t know why some children have gotten sick with MIS-C and others have not.
Though this inflammatory syndrome first appeared in people under age 21, several cases of this condition have been reported in adults. This is called MIS-A, short for multisystem inflammatory syndrome in adults. The condition is much less common in adults than in kids.