Data for: Single versus serial dilution SARS-CoV-2 IgG

Reliable and scalable seroepidemiology methods are needed to estimate
SARS-CoV-2 incidence and monitor the dynamics of population-level immunity
as the pandemic evolves. We aimed to evaluate the reliability of
SARS-CoV-2 normalized ELISA optical density (nOD) at a single dilution
compared to titers derived from serial dilutions. We conducted serial
serosurveys within a community-based cohort in Salvador, Brazil. Anti-S
IgG ELISA (Euroimmun AG) was performed with five serial 3-fold dilutions
of paired sera from 54 participants. Changes in nOD reliably predicted
increases and decreases in titers (98.1% agreement, κ = 95.8%). Fitting
the relationship between nOD and interpolated titers to a log-log curve
yields highly accurate predictions of titers (r2 = 0.995) and changes in
titers (r2 = 0.975), using only one to two dilutions. This approach can
significantly reduce the time, labor and resources needed for large-scale
serosurveys to ascertain population-level changes in exposure and
immunity.