As the infectious disease COVID-19 continues to spread, it is vitally important to understand the humoral immune response. Most COVID-19 patients develop detectable IgM and IgG antibodies targeting the nucleocapsid or the spike protein of SARS-CoV-2 within weeks post infection. Decreases in antibody levels are likely to indicate a lack of protective immunity. Previous studies have shown that IgG responses against SARS-CoV-2 infection can persist for 3 to 8 months post-symptom onset, but long term kinetics of these antibodies are yet to have been investigated. This study aims to provide some information on the kinetics of anti-SARS-CoV-2 IgG antibody levels in subjects with COVID-19 for up to 11 months and the potential influential factors.