Antibody responses to SARS-CoV-2 in patients of novel coronavirus disease 2019

Juanjuan Zhao; Quan Yuan; Haiyan Wang; Wei Liu; Xuejiao Liao; Yingying Su; Xin Wang; Jing Yuan; Tingdong Li; Jinxiu Li; Shen Qian; Congming Hong; Fuxiang Wang; Yingxia Liu; Zhaoqin Wang; Qing He; Zhiyong Li; Bin He; Tianying Zhang; Shengxiang Ge; Lei Liu; Jun Zhang; Ningshao Xia; Zheng Zhang

The copyright holder for this preprint (which was not peer-reviewed) is . https://doi.org/10.1101/2020.03.02.20030189 doi: medRxiv preprint illness (10 earlier than day 10, the other two on day 11 and 13 after onset). The cumulative seroconversion curve showed that the rate for Ab and IgM reached 100% around 1 month of illness day. The seroconversion was sequential appeared for Ab, IgM and then IgG ( Figure 1A ). The median time to Ab, IgM and IgG seroconversion was 11, 12 and 14 days, separately. One of two patients tested on the onset day was seropositive. Overall, the seroconversion of Ab was significantly quicker than that of IgM (p = 0.012) and IgG (p < 0.001), that possibly attributed to the double-antigen sandwich form of the assay used which usually show much higher sensitivity than capture assay (IgM) and indirect assay (IgG). Moreover, all isotypes of antibodies against viral antigen, including IgM, IgA and IgG, can be detected by double-sandwich based assay, which may also contribute to the superior performance of Ab test. In comparisons of seroconversion rates of antibodies between critical and non-critical patients, none of the three markers showed significant difference ( Figure 1B , 1C and ID, p > 0.05).