ObjectiveTo summarize the results of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG antibody, total antibody and cellular immune function of COVID-19 convalescent patients one year after discharge, and to analyze the correlation between the SARS-CoV-2 antibody and the indexes of immune function. MethodsA total of 41 confirmed COVID-19 patients discharged from Chengdu Public Health Clinical Medical Center from January to April 2020 and followed up one year after discharge were included in the study as the research group, including 18 males and 23 females with an average age of 47.83±12.95 years. The results of SARS-CoV-2 IgG, total antibody and immune function indexes one year after discharge were collected in order to discuss the correlation of SARS-CoV-2 and cellular immune function. A total of 40 healthy employees of the hospital vaccinated against COVID-19 were randomly selected as the vaccine group, including 10 males and 30 females with an average age of 43.90±6.86 years. The SARS-CoV-2 antibodies between the two groups were compared. ResultsCD8+T cell count was higher and CD4+T/CD8+T was lower in male patients than those in female patients (all P<0.05). The IgG and total antibodies in patients with re-detectable positive RNA test were both higher than those in patients without re-detectable positive RNA test, but the differences were not statistically significant (P=0.158, 0.060). The positive rate of SARS-CoV-2 IgG in the research group was 80.5% (33/41). SARS-CoV-2 IgG was positively correlated with total antibody (P<0.001). There was a positive correlation between CD4+T cell count and SARS-CoV-2 IgG (r=0.455, P=0.003). The positive rate of SARS-CoV-2 IgG, SARS-CoV-2 IgG amount and total antibody amount in the research group were significantly higher than those in the vaccine group (all P<0.001). ConclusionSARS-CoV-2 IgG of most COVID-19 patients one year after discharge is positive, and their SARS-CoV-2 total antibody is significantly higher than people vaccinated against COVID-19, which suggests that patients infected with SARS-CoV-2 can obtain lasting protection, but the protection may be gradually weaken over time. The degree of antibody attenuation in patients with re-detectable positive RNA test may be weaker. In the convalescence stage, the dynamics of SARS-CoV-2 IgG may be closely related to cellular immune function.