AUTHOR=Xiao Kaihu , Yang Haiyan , Liu Bin , Pang Xiaohua , Du Jianlin , Liu Mengqi , Liu Yajie , Jing Xiaodong , Chen Jing , Deng Songbai , Zhou Zheng , Du Jun , Yin Li , Yan Yuling , Mou Huaming , She Qiang 

TITLE=Antibodies Can Last for More Than 1 Year After SARS-CoV-2 Infection: A Follow-Up Study From Survivors of COVID-19

JOURNAL=Frontiers in Medicine

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2021.684864

DOI=10.3389/fmed.2021.684864

ISSN=2296-858X

ABSTRACT=<p><bold>Background:</bold> COVID-19 is a global pandemic. The prevention of SARS-CoV-2 infection and the rehabilitation of survivors are currently the most urgent tasks. However, after patients with COVID-19 are discharged from the hospital, how long the antibodies persist, whether the lung lesions can be completely absorbed, and whether cardiopulmonary abnormalities exist remain unclear.</p><p><bold>Methods:</bold> A total of 56 COVID-19 survivors were followed up for 12 months, with examinations including serum virus-specific antibodies, chest CT, and cardiopulmonary exercise testing.</p><p><bold>Results:</bold> The IgG titer of the COVID-19 survivors decreased gradually, especially in the first 6 months after discharge. At 6 and 12 months after discharge, the IgG titer decreased by 68.9 and 86.0%, respectively. The IgG titer in patients with severe disease was higher than that in patients with non-severe disease at each time point, but the difference did not reach statistical significance. Among the patients, 11.8% were IgG negative up to 12 months after discharge. Chest CT scans showed that at 3 and 10 months after discharge, the lung opacity had decreased by 91.9 and 95.5%, respectively, as compared with that at admission. 10 months after discharge, 12.5% of the patients had an opacity percentage &gt;1%, and 18.8% of patients had pulmonary fibrosis (38.5% in the severe group and 5.3% in the non-severe group, <italic>P</italic> &lt; 0.001). Cardiopulmonary exercise testing showed that 22.9% of patients had FEV1/FVC%Pred &lt;92%, 17.1% of patients had FEV1%Pred &lt;80%, 20.0% of patients had a VO<sub>2</sub> AT &lt;14 mlO<sub>2</sub>/kg/min, and 22.9% of patients had a VE/VCO<sub>2</sub> slope &gt;30%.</p><p><bold>Conclusions:</bold> IgG antibodies in most patients with COVID-19 can last for at least 12 months after discharge. The IgG titers decreased significantly in the first 6 months and remained stable in the following 6 months. The lung lesions of most patients with COVID-19 can be absorbed without sequelae, and a few patients in severe condition are more likely to develop pulmonary fibrosis. Approximately one-fifth of the patients had cardiopulmonary dysfunction 6 months after discharge.</p>