Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection produces B cell responses that continue to evolve for at least a year. During that time, memory B cells express increasingly broad and potent antibodies that are resistant to mutations found in variants of concern¹. As a result, vaccination of coronavirus disease 2019 (COVID-19) convalescent individuals with currently available mRNA vaccines produces high levels of plasma neutralizing activity against all variants tested^1,2. Here we examine memory B cell evolution five months after vaccination with either Moderna (mRNA-1273) or Pfizer-BioNTech (BNT162b2) mRNA vaccine in a cohort of SARS-CoV-2-naive individuals. Between prime and boost, memory B cells produce antibodies that evolve increased neutralizing activity, but there is no further increase in potency or breadth thereafter. Instead, memory B cells that emerge five months after vaccination of naive individuals express antibodies that are similar to those that dominate the initial response. While individual memory antibodies selected over time by natural infection have greater potency and breadth than antibodies elicited by vaccination, the overall neutralizing potency of plasma is greater following vaccination. These results suggest that boosting vaccinated individuals with currently available mRNA vaccines will increase plasma neutralizing activity but may not produce antibodies with equivalent breadth to those obtained by vaccinating convalescent individuals.

严重的急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 感染会产生 B 细胞反应，这种反应至少会持续进化一年。在此期间，记忆 B 细胞表达越来越广泛和有效的抗体，这些抗体对关注变体中发现的突变具有抗性¹。因此，使用目前可用的 mRNA 疫苗对 2019 年冠状病毒病 (COVID-19) 恢复期个体进行疫苗接种会产生高水平的血浆中和活性，以对抗所有测试的变体^1,2. 在这里，我们在一组未感染 SARS-CoV-2 的个体中检查了接种 Moderna (mRNA-1273) 或 Pfizer-BioNTech (BNT162b2) mRNA 疫苗五个月后记忆 B 细胞的进化。在启动和增强之间，记忆 B 细胞产生的抗体会产生增强的中和活性，但此后效力或广度没有进一步增加。相反，幼稚个体接种疫苗后五个月出现的记忆 B 细胞表达的抗体与主导初始反应的抗体相似。虽然随着时间的推移通过自然感染选择的个体记忆抗体比疫苗接种引发的抗体具有更大的效力和广度，但接种疫苗后血浆的整体中和效力更强。