SARS-CoV-2 infection induces sustained humoral immune responses in convalescent patients following symptomatic COVID-19

Wu, Jun; Liang, Boyun; Chen, Cunrong; Wang, Hua; Fang, Yaohui; Shen, Shu; Yang, Xiaoli; Wang, Baoju; Chen, Liangkai; Chen, Qi; Wu, Yang; Liu, Jia; Yang, Xuecheng; Li, Wei; Zhu, Bin; Zhou, Wenqing; Wang, Huan; Li, Sumeng; Lu, Sihong; Liu, Di; Li, Huadong; Krawczyk, Adalbert; Lu, Mengji; Yang, Dongliang; Deng, Fei; Dittmer, Ulf; Trilling, Mirko; Zheng, Xin

Long-term antibody responses and neutralizing activities in response to SARS-CoV-2 infection are not yet clear. Here we quantify immunoglobulin M (IgM) and G (IgG) antibodies recognizing the SARS-CoV-2 receptor-binding domain (RBD) of the spike (S) or the nucleocapsid (N) protein, and neutralizing antibodies during a period of 6 months from COVID-19 disease onset in 349 symptomatic COVID-19 patients who were among the first be infected world-wide. The positivity rate and magnitude of IgM-S and IgG-N responses increase rapidly. High levels of IgM-S/N and IgG-S/N at 2-3 weeks after disease onset are associated with virus control and IgG-S titers correlate closely with the capacity to neutralize SARS-CoV-2. Although specific IgM-S/N become undetectable 12 weeks after disease onset in most patients, IgG-S/N titers have an intermediate contraction phase, but stabilize at relatively high levels over the 6 month observation period. At late time points, the positivity rates for binding and neutralizing SARS-CoV-2-specific antibodies are still >70%. These data indicate sustained humoral immunity in recovered patients who had symptomatic COVID-19, suggesting prolonged immunity.