Neutralization against BA.2.75.2, BQ.1.1, and XBB from mRNA Bivalent Booster

This serologic study evaluates live-virus neutralization of emergent SARS-CoV-2 omicron subvariants (BA.2.75.2, BQ.1.1, and XBB) in serum samples from participants who received either one monovalent booster, two monovalent boosters, or the updated bivalent booster. Using FRNT50 geometric mean titers (GMTs), researchers found that neutralization was markedly reduced against all subvariants compared to the ancestral WA1/2020 strain, especially against XBB. However, recipients of the bivalent booster showed improved neutralizing activity against all omicron subvariants relative to the monovalent cohorts. Authors conclude that bivalent boosters offer enhanced protection against vaccine-escape variants containing R346T mutations. Limitations include small cohort sizes, variation in previous exposures, and single timepoint analysis.

This serologic study evaluates live-virus neutralization of emergent SARS-CoV-2 omicron subvariants (BA.2.75.2, BQ.1.1, and XBB) in serum samples from participants who received either one monovalent booster, two monovalent boosters, or the updated bivalent booster. Using FRNT50 geometric mean titers (GMTs), researchers found that neutralization was markedly reduced against all subvariants compared to the ancestral WA1/2020 strain, especially against XBB. However, recipients of the bivalent booster showed improved neutralizing activity against all omicron subvariants relative to the monovalent cohorts. Authors conclude that bivalent boosters offer enhanced protection against vaccine-escape variants containing R346T mutations. Limitations include small cohort sizes, variation in previous exposures, and single timepoint analysis.