Fig. 4: The Omicron BA.1.23 subvariant displays strongly reduced neutralizing activity compared to the parental Omicron variant as well as ancestral SARS-CoV-2 variant.

a Absolute neutralization titers (left) and fold-reduction (right) for WA−1, BA.1 and BA.1.23 variants by paired sera from 9 study participants collected before and after booster vaccination (n = 18). The number of samples with titers below the limit of detection of the serological assay (dashed line) is indicated at the bottom of the graph. The error bars represent the geometric mean with 95% confidence intervals. A one-way RM ANOVA with Tukey’s multiple comparison test was used to compare the neutralization titers before and after booster vaccination. ***p-values < 0.001, *p-value: 0.02. b Absolute neutralization titers (left) and fold-reduction (right) for WA-1, BA.1 and BA.1.23 isolates by sera from study participants who experienced breakthrough infection with BA.1. Data for paired sera from 11 participants collected before and after BA.1 infection (n = 22) are shown. The error bars represent the geometric mean with 95% confidence intervals. A one-way RM ANOVA with Tukey’s multiple comparison test was used to compare the neutralization titers before and after BA.1 breakthrough infection. *p-values: 0.02, ns not significant. c Absolute neutralization titers for each of the isolates (WA-1, BA.1 and BA.1.23) by sera collected from patient P2 before and after BA1.23 infection. The first vertical dotted line (left) represents the time of the third vaccine dose as days relative to the index case. The second vertical dotted line (right) indicates the time of infection with the BA.1.23 variant. d Comparison of neutralization fold-change in inhibitory dilution 50% (ID50) measured before and after booster vaccination (left panel, based on 4a) as well as before and after BA.1 (middle panel, based on 4b) and BA.1.23 (right panel, patient 2, based on 4c) breakthrough infection for each of the three viruses tested (WA-1, BA.1 and BA.1.23). Each dot represents IC50 or fold-change data for a specific serum specimen tested by serial dilution in a single replicate experimental setting. GMT denotes mean geometric mean of the inhibitory dilution 50% (ID50) values. The horizontal dotted line represents the limit of detection (10). Samples with neutralization titers below the level of detection were assigned the neutralization value of 5 (equaling to half of the limit of detection) in the ID50 plots. Source data for this figure is provided in the Source Data file.