Coronavirus disease 2019 (COVID-19) is caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)^1,2,3 and individuals with COVID-19 have symptoms that can be asymptomatic, mild, moderate or severe^4,5. In the early phase of infection, T- and B-cell counts are substantially decreased^6,7; however, IgM^8,9,10,11 and IgG^12,13,14 are detectable within 14 d after symptom onset. In COVID-19-convalescent individuals, spike-specific neutralizing antibodies are variable^3,15,16. No specific drug or vaccine is available for COVID-19 at the time of writing; however, patients benefit from treatment with serum from COVID-19-convalescent individuals^17,18. Nevertheless, antibody responses and cross-reactivity with other coronaviruses in COVID-19-convalescent individuals are largely unknown. Here, we show that the majority of COVID-19-convalescent individuals maintained SARS-CoV-2 spike S1- and S2-specific antibodies with neutralizing activity against the SARS-CoV-2 pseudotyped virus, and that some of the antibodies cross-neutralized SARS-CoV, Middle East respiratory syndrome coronavirus or both pseudotyped viruses. Convalescent individuals who experienced severe COVID-19 showed higher neutralizing antibody titres, a faster increase in lymphocyte counts and a higher frequency of CXCR3⁺ T follicular help (T_FH) cells compared with COVID-19-convalescent individuals who experienced non-severe disease. Circulating T_FH cells were spike specific and functional, and the frequencies of CXCR3⁺ T_FH cells were positively associated with neutralizing antibody titres in COVID-19-convalescent individuals. No individuals had detectable autoantibodies. These findings provide insights into neutralizing antibody responses in COVID-19-convalescent individuals and facilitate the treatment and vaccine development for SARS-CoV-2 infection.

2019 年冠状病毒病 (COVID-19) 是由感染严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2) ^1、2、3引起的，而 COVID-19 患者的症状可能是无症状、轻度、中度或重度^{4 ,5} . 在感染的早期阶段，T 细胞和 B 细胞计数显着减少^6,7；然而，IgM ^8,9,10,11和 IgG ^12,13,14在症状出现后 14 天内可检测到。在 COVID-19 恢复期个体中，尖峰特异性中和抗体是可变的^3,15,16。在撰写本文时，没有针对 COVID-19 的特定药物或疫苗；然而，患者受益于 COVID-19 恢复期个体的血清治疗^17,18. 然而，在 COVID-19 恢复期个体中，抗体反应和与其他冠状病毒的交叉反应在很大程度上是未知的。在这里，我们表明大多数 COVID-19 恢复期个体保持 SARS-CoV-2 刺突 S1 和 S2 特异性抗体，对 SARS-CoV-2 假型病毒具有中和活性，并且一些抗体被交叉中和SARS-CoV、中东呼吸综合征冠状病毒或两种假型病毒。与经历非严重疾病的 COVID-19 恢复期个体相比，经历过严重 COVID-19 的恢复期个体显示出更高的中和抗体滴度、淋巴细胞计数增加更快和 CXCR3 ⁺ T 滤泡帮助 (T _{FH ) 细胞的频率更高。}循环 T _FH细胞具有尖峰特异性和功能性，CXCR3 ⁺ T _FH细胞的频率与 COVID-19 恢复期个体的中和抗体滴度呈正相关。没有人有可检测到的自身抗体。这些发现为 COVID-19 恢复期个体的中和抗体反应提供了见解，并促进了 SARS-CoV-2 感染的治疗和疫苗开发。