Figure 3. Peak values of (A) anti–spike IgM, (B) anti–spike IgG, and (C) anti–spike IgA were quantified in plasma from children with MIS-C (n = 16), children with acute COVID-19 (n = 22), and pre-pandemic healthy controls (n = 32).

Results were compared by 1-way ANOVA with multiple comparisons. Time course of (D) anti–spike IgM, (E) anti–spike IgG, and (F) anti–spike IgA were plotted over time following symptom onset for MIS-C. (G) The IC₅₀ for antibody neutralization for children with MIS-C and children with acute COVID-19 were compared by Mann-Whitney t test. Mean values and the SD are presented. *P < 0.05, **P < 0.01, and ****P < 0.0001.