Blood samples were collected once. Enzyme-linked immunosorbent assay (ELISA) was performed using the Architect SARS-CoV-2 IgG and IgG II Quant assay (Abbott-NP, Abbott, Chicago, IL) were used to detect antibody responses against SARS-CoV-2 [14 (link)–16 (link)]. The cutoff value for a positive IgG response was anti-Spike S1 protein IgG (Anti-S) < 50.0 AU/mL and anti-nucleocapsid IgG index (Anti-N) ≥ 1.4 according to the instructions of the manufacturer [14 (link)–16 (link)]. We have proceeded to convert the antibody titer measurements from arbitrary units per milliliter (AU/mL) to WHO’s standard BAU/mL, with BAU/mL being calculated as 0.142 times AU/mL.
Free full text: Click here
