(A) SARS-CoV-2 neutralization assays were performed using pseudoviruses expressing the spike protein of WA-1/2020 or the Omicron subvariants in 293-ACE2-TMPRSS2 cells. SARS-CoV-2 neutralization titers were determined in each of the prepandemic 2019-IVIG (n = 20; black), 2020-IVIG (n = 8; pink), 2020 convalescent plasma (2020-CP; n = 8; blue), 2022 convalescent plasma (2022-CP; n = 9; turquoise), and hCoV-2IG (n = 19; red) preparations. The assay was performed in duplicate to determine the 50% neutralization titer (PsVNA50). The heights of the bars and the numbers over the bars indicate the geometric mean titers, and the whiskers indicate 95% CIs. The horizontal dashed line indicates the limit of detection for the neutralization assay (PsVNA50 of 20). Differences between SARS-CoV-2 strains were analyzed by ordinary 1-way ANOVA, using Tukey’s pairwise multiple-comparison test in GraphPad Prism version 9.3.1, and P values are shown. (B) Relationship of neutralizing antibodies against SARS-CoV-2 WA-1/2020 and Omicron subvariants. Correlation of SARS-CoV-2 WA-1/2020 neutralizing titer versus Omicron subvariant neutralizing titer for 2020-CP (n = 8; blue), 2022-CP (n = 9; turquoise), and hCoV-2IG (n = 19; red). Correlations show Pearson’s correlation coefficient (r) and 2-tailed P values for all samples. The black lines in the scatter plots depict the linear fit of log₂-transformed PsVNA50 values, with shaded area showing 95% CI.