New surveillance case definition developed for MIS-C

A new surveillance case definition for multisystem inflammatory syndrome in children (MIS-C) associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been developed, according to research published in the Dec. 16 issue of the U.S. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.

Michael Melgar, M.D., from the CDC COVID-19 Response Team, and colleagues have developed a Council of State and Territorial Epidemiologists (CSTE) and CDC position statement that includes an MIS-C surveillance case definition for voluntary reporting to the CDC, which comes into effect Jan. 1, 2023.

The methods used to develop the definition included convening MIS-C clinical experts regarding identification of MIS-C and its distinction from other pediatric conditions, a review of the literature comparing the MIS-C phenotype to that of other syndromes, and retrospective application of different criteria to data from previously reported MIS-C cases. The authors note that four important changes are included in the CSTE/CDC surveillance case definition versus the 2020 CDC MIS-C case definition: (1) no required duration of subjective or measured fever; (2) requirement for C-reactive protein ≥3.0 mg/dL; (3) adjustments to criteria of organ system involvement to include shock as a distinct category and eliminate respiratory, neurologic, and renal criteria; and (4) new requirements of timing of positive SARS-CoV-2 laboratory testing relative to MIS-C.

"Continued surveillance will be crucial as new SARS-CoV-2 variants of concern emerge and circulate in the United States and vaccination recommendations expand to include younger children, potentially altering the epidemiology of MIS-C," the authors write.