Figure 1. Neutralizing Responses against the WA1/2020 Strain and Omicron Subvariants.

Shown is the neutralization activity against the WA1/2020 strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the omicron subvariants BA.1, BA.5, BA.2.75.2, BQ.1.1, and XBB in 12 participants who received one monovalent booster (Panel A), in 11 participants who received two monovalent boosters (Panel B), and in 12 participants who received the updated bivalent booster (Panel C). The focus reduction neutralization test (FRNT₅₀ [the reciprocal dilution of serum that neutralizes 50% of the input virus]) geometric mean titer (GMT) of neutralizing antibodies against the WA1/2020 strain and each omicron subvariant is shown at the top of each panel, along with the ratio of the neutralization GMT against the WA1/2020 strain to that against each omicron subvariant. The connecting lines between the variants represent matched serum samples. The horizontal dotted lines represent the limit of detection of the assay (FRNT₅₀ GMT 20). The red lines in Panels B and C indicate the participants who reported previous SARS-CoV-2 infection, and the dashed line in Panel C indicates one participant who received two monovalent boosters before the bivalent booster. The colored bars represent the FRNT₅₀ GMT among the participants in the cohort, and the 𝙸 bars indicate 95% confidence intervals, which were not adjusted for multiplicity and may not be used for hypothesis testing. LOD denotes limit of detection, and NA not applicable.