Multisystem Inflammatory Syndrome in Children-United States, February 2020-July 2021

Background Multisystem inflammatory syndrome in children (MIS-C) is a severe hyperinflammatory condition in persons aged <21 years associated with antecedent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Our objective was to describe MIS-C cases reported to Centers for Disease Control and Prevention's (CDC's) national surveillance since the coronavirus disease 2019 (COVID-19) pandemic began. Methods We included patients meeting the MIS-C case definition with onset date from 19 February 2020 through 31 July 2021, using CDC's MIS-C case report form, which collects information on demographics, clinical presentation, and laboratory results. Trends over time across 3 MIS-C pandemic waves were assessed using Cochran-Armitage test for categorical and Jonckheere-Terpstra test for continuous variables. Results Of 4901 reported cases, 4470 met inclusion criteria. Median patient age increased over time (P < .001), with a median of 9 years (interquartile range, 5-13 years) during the most recent (third) wave. Male predominance also increased (62% in third wave, P < .001). A significant (P < .001) increase in severe hematologic and gastrointestinal involvement was observed across the study period. Frequency of several cardiovascular complications (ie, cardiac dysfunction, myocarditis, and shock/vasopressor receipt) and renal failure declined (P < .001). Provision of critical care including mechanical ventilation (P < .001) and extracorporeal membrane oxygenation (ECMO; P = .046) decreased, as did duration of hospitalization and mortality (each P < .001). Conclusions Over the first 3 pandemic waves of MIS-C in the United States, cardiovascular complications and clinical outcomes including length of hospitalization, receipt of ECMO, and death decreased over time. These data serve as a baseline for monitoring future trends associated with SARS-CoV-2 B.1.617.2 (Delta) or other variants and increased COVID-19 vaccination among children. In 4470 multisystem inflammatory syndrome in children (MIS-C) patients reported with onset dates from 19 February 2020 through 31 July 2021, cardiovascular complications and clinical outcomes including length of hospitalization, receipt of extracorporeal membrane oxygenation, and death decreased over time.

Automated summary

In the MIS-C pandemic in the United States, cardiovascular complications and clinical outcomes, including hospitalization duration, ECMO usage, and death, decreased over time. These data serve as a baseline for monitoring future trends associated with SARS-CoV-2 variants (such as Delta) and increased COVID-19 vaccination among children.