A multidisciplinary team has identified how a rare but serious post-COVID-19 complication develops in children and adolescents. Led by MassGeneral Hospital for Children (MGHfC) pediatric pulmonologist Lael Yonker, M.D., researchers determined that viral particles remaining in the gut long after an initial COVID-19 infection can travel into the bloodstream, instigating the condition called Multisystem Inflammatory Syndrome in Children (MIS-C).
The syndrome can occur several weeks after an initial infection; symptoms include high fever, abdominal pain, vomiting, diarrhea, rash and extreme fatigue. The hyperinflammatory response and "cytokine storm" observed in MIS-C can lead to extensive damage in the heart, liver and other organs.
"When we realized 95% of children with MIS-C had SARS-CoV-2 viral particles in their stool but no or low levels of particles in their noses or throats, we found that viral material lingering in the gut long after the first COVID-19 infection could lead to MIS-C," says Yonker, lead author of the study.
In a study published in the Journal of Clinical Investigation, which included 100 children (19 with MIS-C, 26 with COVID-19 and 55 healthy controls), researchers provide insight into the mechanics of MIS-C and identify potential biomarkers for early disease detection, treatment and prevention. They also describe the successful treatment of a 17-month-old infant with MIS-C.
The team hypothesized that SARS-CoV-2 viral particles found in the gastrointestinal tract of children move into the bloodstream, leading to the hyperinflammatory immune response characteristic of MIS-C. According to researchers, this is the first study showing viral particles in the blood of MIS-C patients coinciding with the hyperinflammatory response.
While MIS-C occurs in less than 1% of children with confirmed SARS-CoV-2 infection, 80% of children hospitalized with MIS-C develop severe cardiac pathology. They also face a long hospital stay and extensive recovery period. Current treatments include an aggressive, long-term course of steroids and intravenous immunoglobulin, but researchers are hopeful this study will lead to the development of new treatments.
As of May 2021, the U.S. Centers for Disease Control and Prevention reported 3,742 children diagnosed with MIS-C and 35 deaths. U.S. statistics are skewed heavily toward Latino and Black children, with a total of 63% in cases with race or ethnicity listed.