Substantial Neutralization Escape by SARS-CoV-2 Omicron Variants BQ.1.1 and XBB.1

This study assessed the neutralization resistance of SARS-CoV-2 Omicron subvariants BQ.1.1 and XBB.1, which harbor the R346T spike mutation and became dominant globally in late 2022. Across three cohorts (2021 monovalent booster, 2022 monovalent booster, 2022 bivalent booster), neutralizing antibody titers against these subvariants were substantially reduced compared to earlier variants. BQ.1.1 and XBB.1 exhibited escape factors of up to 21-fold relative to BA.5 and over 230-fold compared to the ancestral WA1/2020 strain. Despite booster-induced increases in overall antibody levels, responses to BQ.1.1 and XBB.1 remained markedly lower. The authors suggest vaccine efficacy against these variants may rely more on CD8+ T-cell responses and call attention to convergent evolution among emerging Omicron lineages.

This study assessed the neutralization resistance of SARS-CoV-2 Omicron subvariants BQ.1.1 and XBB.1, which harbor the R346T spike mutation and became dominant globally in late 2022. Across three cohorts (2021 monovalent booster, 2022 monovalent booster, 2022 bivalent booster), neutralizing antibody titers against these subvariants were substantially reduced compared to earlier variants. BQ.1.1 and XBB.1 exhibited escape factors of up to 21-fold relative to BA.5 and over 230-fold compared to the ancestral WA1/2020 strain. Despite booster-induced increases in overall antibody levels, responses to BQ.1.1 and XBB.1 remained markedly lower. The authors suggest vaccine efficacy against these variants may rely more on CD8+ T-cell responses and call attention to convergent evolution among emerging Omicron lineages.