Supplementary material: Accurate prediction of serum antibody levels from noninvasive saliva/nasal samples

Supplemental Figure 1. Measured serum Sars-CoV-2 antibody level compared with the level predicted from saliva and nasal samples. The predicted serum covid antibody levels from saliva (A) and nasal (B) were obtained by first normalizing the saliva/nasal samples to their total IgG content, and then correcting these values to the measured total IgG serum concentration derived from the paired serum sample. The Coefficient of determination, R2 is shown on each graph, p (two-tailed) < 0.0001 in each case (n=64 for saliva/serum, n=55 for nasal/serum paired samples) (GraphPad Prism). Axes are log scale.

Supplemental Table 1. Example of normalization of specific Covid S1 antibodies in saliva to total IgG and prediction of serum levels. Column one shows ELISA measurements of Covid S1 specific antibodies in the saliva of 3 donated samples, values are expressed as BAU/ml. The second column is the total IgG level measured in the saliva samples, expressed as ug/ml of IgG. The third column shows the values obtained when the specific Covid S1 antibody level is divided by the total IgG found in the saliva sample, to give the specific antibody measurement per ug of total IgG (units BAU/ug). To predict the serum levels from that detected in saliva, the average total IgG concentration obtained for all serum donations (expressed in ug/ml, in column 4) was used to multiply the specific Covid S1/total IgG in saliva (column 3). The predicted (column 5) obtained from this calculation can be compared to the value measured in the paired serum sample (column 6).