Timing of Multisystem Inflammatory Syndrome in Children in Relation to Index Covid-19 Infection

ABSTRACT

INTRODUCTION: Multisystem Inflammatory Syndrome in Children (MIS-C) RESULTS from Immune Dysregulation Following COVID-19 Infection. Timing of MIS-C Diagnosis in Relation to Index COVID-19 Infection Varies. The CDC Reports the Average Time Between MIS-C and COVID-19 Infection is 4 Weeks. We Aim to Determine if the Timing of MIS-C Diagnosis in Relation to the Index COVID-19 Infection Varies by Variant, and Whether Spike IgG Value Correlates with the Time Between COVID-19 and MIS-C or with Peak Ferritin. METHOD(S) Our MIS-C Team (Pediatric Cardiologists, Rheumatologists, Immunologists, Hematologists, Intensivists, and Hospitalists) Reviewed Every Suspected Case of MIS-C at our Institution, and All Confirmed Cases Were Reported to the State Health Department. Electronic Health Records Were Reviewed to Obtain Data Elements in this IRB Exempt Study. COVID-19 Variant Timeframes Were Defined by Dominant (>50% cases) Strand in the United States (Alpha/ Beta/Gamma 1/21/20-6/25/21, Delta 6/26/21-12/17/21, and Omicron 12/18/21-Present). RESULT(S) Our MIS-C Team Identified 68 Cases from 7/2/20 to 6/22/22 out of 226 (30%) Confirmed in South Carolina. We Categorized Each Case by COVID-19 Definition (Exposure, Positive Test, or Unknown). The COVID-19 Component of the Definition was Based on Exposures in 25 (37%), 25 (37%) Positive Antigen Test or PCR, and 18 (26%) Positive IgG. Mean Time Between COVID Exposure or Positive Test and MIS-C Diagnosis was 31.5d. Mean Time for Alpha/Beta/Gamma Variant was 27.3d, Delta 33.6d, and Omicron 34.2d. 100% of Cases Received IVIG, 72% IVIG and Steroids, and 13% IVIG, Steroids, and Anakinra. Relationship Between Spike IgG and Timeframe of MIS-C (r=0.61), Peak Ferritin and Anakinra (r=0.63), and Peak Ferritin and Timeframe of MIS-C (r=0.34). Only 4% of Those Vaccine-Eligible at the Time of Illness Were Fully Vaccinated. CONCLUSION(S) The Timing of MIS-C Diagnosis in Relation to the Index of COVID-19 Infection does Vary by Variant with a 6.9 Day Increase in Average Since the Start of the Pandemic. Our Overall Average of 31.5 Days (4.5 Weeks) Between COVID-19 and MIS-C Supports the Initial CDC Estimate of 4 Weeks. There was a Moderate Positive Correlation Between Spike IgG and Timeframe of MIS-C, and a Higher Peak Ferritin Indicated use of Anakinra.