Statistics
Differences between participants with and without SARS-CoV-2 infection were analyzed using the Mann-Whitney U and chi-square tests with a two-sided P value. Demographic variables and antibody responses were also evaluated. Continuous outcome measures are summarized as median and interquartile range (IQR), and antibody concentrations were log10-transformed for the analysis. A P value of <0.05 was considered significant.
The comparison of anti-S antibody and neutralizing antibody concentrations was analyzed using the Kruskal-Wallis test followed by a post-hoc Mann-Whitney U test. Statistical analysis was conducted using SPSS version 28 and Prism version 7 (GraphPad). Temporal relationships between antibody concentrations were plotted as quadratic curves using a polynomial regression approach.