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. 2021 Jul 9;16(7):e0254367. doi: 10.1371/journal.pone.0254367

Fig 3. Antibodies (IgG) against SARS-CoV-2 S-RBD protein in COVID-19 patients and negative controls as detected by the multiplex assay.

Fig 3

Multiplex assay was performed to detect antibodies against SARS-CoV-2 S-RBD, SARS-CoV S & N, MERS-CoV S-RBD and S proteins of 4 common coronaviruses. IgG antibodies to SARS-CoV-2 (S-RBD) antigen as determined in a multiplex microbead assay format are shown as MFI here.—MFI values in log10 scale with IQR are shown. Assay cutoff values for SARS-CoV-2 S-RBD IgG are indicated by dashed lines. Samples from pre-pandemic healthy individuals and patients with other respiratory diseases (COPD, TB, RSV, and influenza) were compared to COVID-19 patients from the USA and Pakistan. In patients where multiple time points were available, the latest time point after the onset of symptoms is shown. Statistical significance was tested by one-way ANOVA and Tukey’s multiple comparison test (P value <0·0001 is denoted by ****).