Fig. 1.

Changes in SARS-CoV-2-specific antibodies. (a) Antibodies were analyzed at baseline (Ischgl 1) and after 6.5 months follow up (Ischgl 2) using four immunoassays for binding antibodies and a neutralization assay. (b) Titers of anti-S IgG using Euroimmun ELISA. OD > 0.8 was counted as positive (dotted line), n = 801. (c) Titers of anti-N IgG using Abbott immunoassay. OD > 1.4 was counted as positive (dotted line), n = 801. (d) Titers of anti-N IgG using Roche immunoassay. OD > 1 was counted as positive (dotted line), n = 40 pairs of samples were analyzed. (e) Correlation of anti-N IgG determined via Abbott versus Roche assay at follow-up, n = 309. (b-e) Spearman r and 95% CI are depicted. (f) Titers of neutralizing antibodies. Titers ≤1:4 were counted as negative, n = 671 sample pairs were analyzed. (g) Change of neutralizing antibody titers between baseline and follow-up was analyzed for samples from f with positive (≥1:16) neutralizing antibody titers either in baseline or follow-up study. (h) Neutralizing antibody titers against wild-type (D614G) and B.1.351 were determined at baseline (Ischgl 1) and follow-up (Ischgl 2) using replication competent SARS-CoV-2 isolates (n = 66). Titers ≤1:4 were considered negative (dotted line). Statistics were determined using One-Way ANOVA (Friedman test with Dunn's multiple comparison), ns = non-significant, *** p < 0.001, **** p < 0.0001. (i) Avidity of anti-S IgG was analyzed at baseline and follow-up for all samples with positive anti-S IgG titers at both time points, n = n = 218. Temporal trend in the median (IQR) concentration of anti-SARS-CoV-2 IgG antibodies as compared to the median binding affinities (avidities) of the antibodies (%). The lower and upper bars represent the minimum and maximum values, respectively. Dots represent outliers. Statistics were determined using Students t-test for paired samples, **** p < 0.0001.