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

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 (1,2).In May 2020, CDC created an MIS-C case definition and established a passive national surveillance system for voluntary case reporting by state and local health departments.*In 2022, CDC and the Council of State and Territorial Epidemiologists (CSTE) created a new surveillance case definition that went into effect on January 1, 2023 † (3).Approximately 87% of cases reported using the 2020 case definition also meet the 2023 case definition.This report describes 2023 MIS-C cases and compares them with cases reported earlier in the COVID-19 pandemic.