Dynamic changes and prevalence of SARS-CoV-2 IgG/IgM antibodies: multiple factors-based analysis

Luo, Chunhua; Liu, Min; Li, Qianyuan; Zheng, Xiaoling; Ai, Wen; Gong, Feng; Fan, Jinhong; Liu, Shaowei; Wang, Xi; Luo, Jun

Objective Investigating the dynamic characteristics of serologic antibodies against SARS-CoV-2 is of significance. Method Here, the dynamic changes and prevalence of IgM and IgG antibodies against SARS-CoV-2 from symptoms onset to 210 days were described. Antibodies were detected by a chemiluminescence immunoassay. Result For all patients, the average titers and positive rates of IgG/IgM within 30 days from symptoms onset reached to the peak and then began continuous decline. The titers and positive rates of IgG/IgM from symptoms 180 to 210 days remained 43.1 ± 27.0 AU/mL/84.3% and 4.4 ± 5.2 AU/mL/12.0%, respectively. Further statistical analysis revealed that the dynamic changes and prevalence in the SARS‐CoV‐2 IgG/IgM antibodies are mainly based on age and disease severity, not sex. The change trend of dynamic and prevalence of IgM antibody was similar as the description of IgG. Even so, the decline rate of IgM antibody is faster. The IgG level that reduced to 16.33 ± 3.15 AU/mL might be a threshold value and should be alerted because the IgG level might become undetectable within 30 to 60 days when the IgG down to the threshold value. Conclusion These results could provide important information for COVID-19 diagnosis, treatment, and vaccine development.