The SARS-CoV-2 Omicron variant can escape neutralization by vaccine-elicited and convalescent antibodies. Memory B cells (MBCs) represent another layer of protection against SARS-CoV-2, as they persist after infection and vaccination and improve their affinity. Whether MBCs elicited by mRNA vaccines can recognize the Omicron variant remains unclear. We assessed the affinity and neutralization potency against the Omicron variant of several hundred naturally expressed MBC-derived monoclonal IgG antibodies from vaccinated COVID-19-recovered and -naive individuals. Compared with other variants of concern, Omicron evaded recognition by a larger proportion of MBC-derived antibodies, with only 30% retaining high affinity against the Omicron RBD, and the reduction in neutralization potency was even more pronounced. Nonetheless, neutralizing MBC clones could be found in all the analyzed individuals. Therefore, despite the strong immune escape potential of the Omicron variant, these results suggest that the MBC repertoire generated by mRNA vaccines still provides some protection against the Omicron variant in vaccinated individuals.

SARS-CoV-2 Omicron 变体可以逃避疫苗引发和恢复期抗体的中和作用。记忆 B 细胞 (MBC) 代表了针对 SARS-CoV-2 的另一层保护，因为它们在感染和疫苗接种后持续存在并提高了亲和力。由 mRNA 疫苗引发的 MBC 是否可以识别 Omicron 变体仍不清楚。我们评估了数百种天然表达的 MBC 衍生单克隆 IgG 抗体对 Omicron 变体的亲和力和中和效力，这些抗体来自接种过 COVID-19 的恢复和未接种过疫苗的个体。与其他关注的变体相比，Omicron 逃避了更大比例的 MBC 衍生抗体的识别，只有 30% 保留了对 Omicron RBD 的高亲和力，而且中和效力的降低更为明显。尽管如此，在所有分析的个体中都可以找到中和性 MBC 克隆。因此，尽管 Omicron 变体具有强大的免疫逃逸潜力，但这些结果表明，由 mRNA 疫苗产生的 MBC 库仍然提供了一些针对接种个体的 Omicron 变体的保护。