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

Objective To investigate the dynamic characteristics of serological antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is of much current significance. Methods The dynamic changes and prevalence of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against SARS-CoV-2 were assessed from the time of symptom onset up to 210 days. Antibodies were detected using a chemiluminescence immunoassay. Results The average titers and IgG/IgM positivity rates reached a peak within 30 days of symptom onset and then began to decline continuously. Between 180 and 210 days following symptom onset, the titers of IgG and IgM were 43.1 ± 27.0 AU/mL and 4.4 ± 5.2 AU/mL, respectively, while the respective positivity rates were 84.3% and 12.0%. Further statistical analyses revealed that the dynamic changes and prevalence of the SARS-CoV-2 IgG/IgM antibodies were related to age and disease severity, but not to sex. The dynamic changes and the prevalence were similar for both the IgM and the IgG antibodies. Even so, there was a more rapid rate of decline for the IgM antibodies. It was found that an IgG level of 16.33 ± 3.15 AU/mL may represent a threshold value that should act as an alert, as it may indicate that the IgG level will become undetectable within the next 30–60 days. Conclusion The results provide important information concerning COVID-19 and may be of relevance for diagnosis, treatment, and vaccine development.