Marked Increase in Avidity of SARS-CoV-2 Antibodies 7–8 Months After Infection Is Not Diminished in Old Age

Abstract The kinetics of immunoglobulin G (IgG) avidity maturation during severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection obtained from 217 participants the Ischgl cohort, Austria, was studied 0.5–1.5 months (baseline) and 7–8 (follow-up) after infection. IgG assay, using a modified enzyme-linked immunosorbent assay (ELISA) 5.5 M urea, revealed that old age does not diminish increase in avidity, detected all positive at both time points, 18% to 42%. High associated with marked residual neutralization capacity 97.2.% (211/217), which even higher older group, revealing an important role assays as easy cheap surrogate tests for assessing immune system conveying potential protection against further SARS-CoV-2 infections without necessitating expensive laborious assays.