Antiglycan IgG and IgM antibody signals that correlate with disease severity. (A) Box and whisker plots of the average IgG signals (log-transformed base 2) to ovalbumin for controls, NIH COVID-19 patients designated as either asymptomatic/mild, moderate/severe, or critical, and controls from a prior study. (B) Box and whisker plots of the average array IgM signals (log-transformed base 2) to iso-Forssman, the Forssman disaccharide, and NA2 for controls, NIH COVID-19 patients designated as either asymptomatic/mild, moderate/severe, or critical, and controls from a prior study. Method of discovery is ANOVA using the step-up method of Benjamini and Hochberg with a false discovery rate (FDR) = 0.05 to account for multiple comparisons, and demonstration of consistent trends with increasing disease severity. *, P < 0.05; **, P < 0.01; ***, P < 0.001; and ****, P < 0.0001. See symbol legend in Fig. 4. Glycan structures were created using GlycoGlyph (45). Boxes depict quartiles and whiskers depict the min and max.