Fig. 3: Estimation of the associations of baseline anti-N and anti-S antibody levels on infection risk during the study period.

a, b, d, e, g, h The conditional effects of anti-N antibody levels and anti-S antibody titers during the observation period on the absolute risk of both symptomatic and asymptomatic infection (a, b), symptomatic infection (d, e), and asymptomatic infection (g, h), respectively. Each predicted data point (blue dots), along with the median absolute risk (line) and 95% CredIs (ribbon), is shown. The overall risk of a control group with no vaccination or prior infection history in this cohort (0.184) (green solid line) and the 90% reduction of relative risk (i.e., 10% relative risk [10% RR]) (green dotted line) are shown. c, f, i The combined effect of anti-N and anti-S antibody levels during the observation period on the absolute risk of both symptomatic and asymptomatic infection (c), symptomatic infection (f), and asymptomatic infection (i), respectively. The logarithmic absolute risk of infection is indicated by the color bar. The white dotted and solid lines show the log₁₀ absolute risk decrease for every 0.5 and 1.0, respectively. j, k Baseline anti-N antibody levels and anti-S antibody titers by the number of vaccine doses and infection history. l Baseline anti-S antibody titers by the number of vaccine doses, Omicron-adapted bivalent vaccination, and infection history. Each data point (dots) and the box plots are shown. Overall (a–c, j–l) and symptomatic infection (d–f); n = 4496. Asymptomatic infection (g–i); n = 4327.