Persistence of Antibody and Cellular Immune Responses in COVID-19 patients over Nine Months after Infection

Yao, Lin; Wang, Guo-Lin; Shen, Yuan; Wang, Zhuang-Ye; Zhan, Bing-Dong; Duan, Li-Jun; Lu, Bing; Shi, Chao; Gao, Yu-Meng; Peng, Hong-Hong; Wang, Guo-Qiang; Wang, Dong-Mei; Jiang, Ming-Dong; Cao, Guo-Ping; Ma, Mai-Juan

BACKGROUND: The duration of humoral and T and cell response after the infection of SARS-CoV-2 remains unclear. METHODS: We performed a cross-sectional study to assess the virus-specific antibody and memory T and B cell responses in COVID-19 patients up to 343 days after infection. Neutralizing antibodies and antibodies against the receptor-binding domain, spike, and nucleoprotein of SARS-CoV-2 were measured. Virus-specific memory T and B cell responses were analyzed. RESULTS: We enrolled 59 COVID-19 patients, including 38 moderate, 16 mild, and five asymptomatic patients; 31 (52.5%) were men, and 28 (47.5%) were women. The median age was 41 (interquartile range [IQR]: 30–55). The median day from symptom onset to enrollment was 317 days (range 257 to 343 days). We found that approximately 90% of patients still have detectable IgG antibodies against spike and nucleocapsid proteins and neutralizing antibodies against pseudovirus, whereas ~60% of patients had detectable IgG antibodies against receptor binding domain and surrogate virus-neutralizing antibodies. SARS-CoV-2-specific IgG (+) memory B cell and IFN-γ secreting T cell responses were detectable in over 70% of patients. CONCLUSIONS: SARS-CoV-2-specific immune memory response persists in most patients nearly one year after infection, which provides a promising sign for prevention from reinfection and vaccination strategy.