Notes from the Field: Surveillance for Multisystem Inflammatory Syndrome in Children - United States, 2023

What is already known about this topic? Multisystem inflammatory syndrome in children (MIS-C) is a rare but serious condition typically occurring 2–6 weeks after SARS-CoV-2 infection and characterized by fever and multiorgan involvement. What is added by this report? MIS-C incidence has decreased from early in the COVID-19 pandemic (highest in late 2020–early 2021), but cases continue to occur with a recent relative increase in the fall of 2023 after a period of increased COVID-19 activity in the general population. Among 117 patients with MIS-C in 2023, approximately one half required intensive care unit–level care. More than 80% (92 of 112) of MIS-C cases were in vaccine-eligible but unvaccinated children, and among the 20 vaccinated children, 60% likely had waned immunity at the time of MIS-C illness. What are the implications for public health practice? MIS-C cases continue to occur but at low rates, making ongoing surveillance valuable. COVID-19 vaccination remains important for preventing MIS-C.