In addition to serum immunoglobulins, memory B cell (MBC) generation against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is another layer of immune protection, but the quality of MBC responses in naive and coronavirus disease 2019 (COVID-19)-recovered individuals after vaccination remains ill defined. We studied longitudinal cohorts of naive and disease-recovered individuals for up to 2 months after SARS-CoV-2 mRNA vaccination. We assessed the quality of the memory response by analysis of antibody repertoires, affinity, and neutralization against variants of concern (VOCs) using unbiased cultures of 2,452 MBCs. Upon boosting, the MBC pool of recovered individuals expanded selectively, matured further, and harbored potent neutralizers against VOCs. Although naive individuals had weaker neutralizing serum responses, half of their RBD-specific MBCs displayed high affinity toward multiple VOCs, including delta (B.1.617.2), and one-third retained neutralizing potency against beta (B.1.351). Our data suggest that an additional challenge in naive vaccinees could recall such affinity-matured MBCs and allow them to respond efficiently to VOCs.

除血清免疫球蛋白外，针对严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2) 的记忆 B 细胞 (MBC) 生成是另一层免疫保护，但 MBC 在幼稚和冠状病毒病 2019 (COVID-19) 中的反应质量)-接种疫苗后恢复的个体仍然不明确。我们在 SARS-CoV-2 mRNA 疫苗接种后长达 2 个月的时间里研究了初次接触和疾病康复个体的纵向队列。我们通过使用 2,452 个 MBC 的无偏培养物分析抗体库、亲和力和针对关注变体 (VOC) 的中和来评估记忆反应的质量。在加强后，恢复个体的 MBC 池有选择地扩大，进一步成熟，并含有针对 VOC 的有效中和剂。尽管天真的个体具有较弱的中和血清反应，他们一半的 RBD 特异性 MBC 对多种 VOC 表现出高亲和力，包括 delta (B.1.617.2)，三分之一保留了对 beta (B.1.351) 的中和效力。我们的数据表明，对未接种过疫苗的人进行额外的挑战可以回忆起这种亲和力成熟的 MBC，并使它们能够有效地对 VOC 做出反应。