CD4 and COVID-19: Therefore, this study conducted a one-year follow-up study on COVID-19 recovery patients in Sichuan, China, to observe the dynamic changes of SARS-CoV-2 specific antibodies and leukocyte subsets (NK cells, B cells, CD4+ and CD8+ T cells) with the recovery time, and to analyze the related factors affecting the viral-specific antibodies after one year of recovery.