SARS-CoV-2 Antibody Titers and Severity of Multisystem Inflammatory Syndrome in Children

Multisystem inflammatory syndrome in children (MIS-C) is a rare yet serious pathological consequence of SARS-CoV-2 infection which is reported 4-12 weeks after the onset of COVID-19 in children and adolescents. The most common hyper-inflammatory conditions mimicking the clinical presentation of MIS-C include Kawasaki disease and toxic shock syndrome. The surveillance criteria of MIS-C were recently revised by US Center for Disease Control and Prevention to improve diagnostic precision. Although previous studies have shown that SARS-CoV-2 antibody titers correlate with COVID-19 severity, their relation to MIS-C severity remains poorly understood and the aim of the study was to investigate this.

As all the MIS-C patients get a SARS-CoV-2 antibody test performed on the first day of hospitalization, here we attempted to stratify risk for adverse outcomes due to MIS-C based on the SARS-CoV-2 antibody titers.

Our studies demonstrated that SARS-CoV-2 antibody titers, specifically Total (IgG/IgM/partial IgA), Nucleocapsid IgG, and Spike IgM, do not correlate with MIS-C severity assessed based on the ICU admission, inotropic support, and mechanical respiratory support requirements.

Therefore, it might not be appropriate to predict the clinical course of patients presenting with MISC based on quantitative serology testing.