{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,30]],"date-time":"2025-07-30T16:12:28Z","timestamp":1753891948161,"version":"3.41.2"},"reference-count":26,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2023,5,24]],"date-time":"2023-05-24T00:00:00Z","timestamp":1684886400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Pediatr."],"abstract":"<jats:sec><jats:title>Introduction<\/jats:title><jats:p>Multisystem inflammatory syndrome in children (MIS-C) is a new condition that first appeared in children and adolescents during the COVID-19 pandemic. We aimed to describe the diagnostic course, clinical and biological manifestations, and treatment of MIS-C during the first three COVID-19 waves.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>We extracted patient data from the Juvenile Inflammatory Rheumatism (JIR) cohort. We analyzed data for patients meeting the World Health Organization diagnostic criteria for MIS-C from the start of the COVID-19 pandemic from March 2020 to June 30, 2021. We then compared data for patients in wave one to those in waves two and three.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>We identified 136 patients with MIS-C. The median age decreased but not significantly during the waves, from 9.9 years to 7.3 years (<jats:italic>p<\/jats:italic>\u2009=\u20090.105). Boys represented 52.2% (<jats:italic>n<\/jats:italic>\u2009=\u200971) of patients, and 46% (<jats:italic>n<\/jats:italic>\u2009=\u200941) of patients originated from sub-Saharan Africa (<jats:italic>p<\/jats:italic>\u2009&amp;lt;\u20090.001). Patients presented less diarrhea (<jats:italic>p<\/jats:italic>\u2009=\u20090.004), respiratory distress (<jats:italic>p<\/jats:italic>\u2009&amp;lt;\u20090.001), and myocarditis (<jats:italic>p<\/jats:italic>\u2009&amp;lt;\u20090.001) with progressive waves. Biological inflammation also decreased, namely, C-reactive protein level (<jats:italic>p<\/jats:italic>\u2009&amp;lt;\u20090.001), neutrophil count (<jats:italic>p<\/jats:italic>\u2009=\u20090.004), and albumin level (<jats:italic>p<\/jats:italic>\u2009&amp;lt;\u20090.001). Patients received more corticosteroids (<jats:italic>p<\/jats:italic>\u2009&amp;lt;\u20090.001) and required less ventilation support (<jats:italic>p<\/jats:italic>\u2009&amp;lt;\u20090.01) and less inotrope treatment (<jats:italic>p<\/jats:italic>\u2009&amp;lt;\u20090.001) in the later waves. The duration of hospitalization gradually decreased (<jats:italic>p<\/jats:italic>\u2009&amp;lt;\u20090.001), as did critical care unit admissions (<jats:italic>p<\/jats:italic>\u2009=\u20090.002).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Over the three COVID-19 waves, with a change in the management of MIS-C, children in the JIR cohort in France showed a less severe disease course, in particular, a greater use of corticosteroids. This observation may reflect the impact of both improved management and different SARS-CoV-2 variant.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fped.2023.1126985","type":"journal-article","created":{"date-parts":[[2023,5,24]],"date-time":"2023-05-24T12:58:10Z","timestamp":1684933090000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":2,"title":["Multisystem inflammatory syndrome in children during the COVID-19 waves: data from the Juvenile Inflammatory Rheumatism 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