Fig. 3. Longitudinal observation of SARS-CoV-2 IgG assays in COVID-19 cases. (A) Changes in the SARS-CoV-2 IgG index in 18 COVID-19 cases that showed seroconversion (i.e., serological assay result change from negative to positive). (B) Longitudinal observation of SARS-CoV-2 IgG in 14 COVID-19 cases positive for SARS-CoV-2 IgG in the first antibody assay. The dashed line indicates the IgG assay cutoff value (index=1.40).
Abbreviations: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; COVID-19, Coronavirus disease 2019.

Ann Lab Med 2021;41:568~576 https://doi.org/10.3343/alm.2021.41.6.568