Twelve-month specific IgG response to SARS-CoV-2 receptor-binding domain among COVID-19 convalescent plasma donors in Wuhan

Li, Cesheng; Yu, Ding; Wu, Xiao; Liang, Hong; Zhou, Zhijun; Xie, Yong; Li, Taojing; Wu, Junzheng; Lu, Fengping; Feng, Lu; Mao, Min; Lin, Lianzhen; Guo, Huanhuan; Yue, Shenglan; Wang, Feifei; Peng, Yan; Hu, Yong; Wang, Zejun; Yu, Jianhong; Zhang, Yong; Lu, Jia; Ning, Haoran; Yang, Huichuan; Fu, Daoxing; He, Yanlin; Zhou, Dongbo; Du, Tao; Duan, Kai; Dong, Demei; Deng, Kun; Zou, Xia; Zhang, Ya; Zhou, Rong; Gao, Yang; Zhang, Xinxin; Yang, Xiaoming

To investigate the duration of humoral immune response in convalescent coronavirus disease 2019 (COVID-19) patients, we conduct a 12-month longitudinal study through collecting a total of 1,782 plasma samples from 869 convalescent plasma donors in Wuhan, China and test specific antibody responses. The results show that positive rate of IgG antibody against receptor-binding domain of spike protein (RBD-IgG) to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the COVID-19 convalescent plasma donors exceeded 70% for 12 months post diagnosis. The level of RBD-IgG decreases with time, with the titer stabilizing at 64.3% of the initial level by the 9th month. Moreover, male plasma donors produce more RBD-IgG than female, and age of the patients positively correlates with the RBD-IgG titer. A strong positive correlation between RBD-IgG and neutralizing antibody titers is also identified. These results facilitate our understanding of SARS-CoV-2-induced immune memory to promote vaccine and therapy development.