Fig. 1: Reduced neutralization of Omicron SARS-CoV-2 by previous non-Omicron viral infection.

50% fluorescent focus reduction neutralization titers (FFRNT₅₀) were measured for two serum panels from patients previously infected with non-Omicron SARS-CoV-2. The first serum panel was collected at 1-month post-infection (n = 64) and the second panel collected at 6-months post-infection (n = 36). For each serum, FFRNT₅₀ values were determined against mNG USA-WA1/2020 (in gray color) and Omicron-spike SARS-CoV-2 (in red color). a FFRNT₅₀s of 1-month postinfection sera (shown as circles). b FFRNT₅₀s of 6-month postinfection sera (shown as triangles). Supplementary Tables 1 and 2 summarize the FFRNT₅₀ values and serum information for (a) and (b), respectively. Each symbol of dots (a) and triangles (b) represents one serum specimen. The FFRNT₅₀ value for each serum was determined in duplicate assays and is presented as the geometric mean. The bar heights and the numbers above each set of data indicate geometric mean titers. The whiskers indicate 95% confidence intervals. The dotted line indicates the first serum dilution (1:20) of the FFRNT assay. The FFRNT₅₀ values of sera that did not show any inhibition of viral infection are presented as 10 for plot purposes and statistical analysis. Statistical analysis was performed using the Wilcoxon matched-pairs signed-rank test. The statistical significance of the difference between the geometric mean titers against USA-WA1/2020 and Omicron-spike SARS-CoV-2 is p < 0.0001 in both (a) and (b).