From the Journals

New study offers details on post-COVID pediatric illness



Multisystem inflammatory syndrome in children (MIS-C) is more common than previously thought. This pediatric illness occurs 2-6 weeks after being infected with COVID-19.

For every 100 COVID-19 hospitalizations, there were 17 MIS-C hospitalizations, a new study found. The illness is rare, but it causes dangerous multiorgan dysfunction and frequently requires a stay in the ICU. According to the Centers for Disease Control and Prevention, there have been at least 9,333 cases nationwide and 76 deaths from MIS-C.

Researchers said their findings were in such contrast to previous MIS-C research that it may render the old research “misleading.”

The analysis was powered by improved data extracted from hospital billing systems. Previous analyses of MIS-C were limited to voluntarily reported cases, which is likely the reason for the undercount.

The study reported a mortality rate for people with the most severe cases (affecting six to eight organs) of 5.8%. The authors of a companion editorial to the study said the mortality rate was low when considering the widespread impacts, “reflecting the rapid reversibility of MIS-C” with treatment.

Differences in MIS-C cases were also found based on children’s race and ethnicity. Black patients were more likely to have severe cases affecting more organs, compared to white patients.

The study included 4,107 MIS-C cases, using data from 2021 for patients younger than 21 years old. The median age was 9 years old.

The findings provide direction for further research, the editorial writers suggested.

Questions that need to be answered include asking why Black children with MIS-C are more likely to have a higher number of organ systems affected.

“Identifying patient biological or socioeconomic factors that can be targeted for treatment or prevention should be pursued,” they wrote.

The CDC says symptoms of MIS-C are an ongoing fever plus more than one of the following: stomach pain, bloodshot eyes, diarrhea, dizziness or lightheadedness (signs of low blood pressure), skin rash, or vomiting.

A version of this article first appeared on

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