Serology characteristics of SARS-CoV-2 infection after exposure and post-symptom onset

• Published in: The European respiratory journal Vol. 56; no. 2; p. 2000763
• Main Authors: Lou, Bin, Li, Ting-Dong, Zheng, Shu-Fa, Su, Ying-Ying, Li, Zhi-Yong, Liu, Wei, Yu, Fei, Ge, Sheng-Xiang, Zou, Qian-Da, Yuan, Quan, Lin, Sha, Hong, Cong-Ming, Yao, Xiang-Yang, Zhang, Xue-Jie, Wu, Ding-Hui, Zhou, Guo-Liang, Hou, Wang-Heng, Li, Ting-Ting, Zhang, Ya-Li, Zhang, Shi-Yin, Fan, Jian, Zhang, Jun, Xia, Ning-Shao, Chen, Yu
• Format: Journal Article
• Language: English
• Published: England 01.08.2020
• Subjects: Adult; Aged; Betacoronavirus; China; Clinical Laboratory Techniques; Coronavirus Infections - blood; Coronavirus Infections - complications; Coronavirus Infections - diagnosis; COVID-19; COVID-19 Testing; Female; Hospitalization; Humans; Infectious Disease Incubation Period; Male; Middle Aged; Pandemics; Pneumonia, Viral - blood; Pneumonia, Viral - complications; Pneumonia, Viral - diagnosis; SARS-CoV-2; Sensitivity and Specificity; Seroconversion; Symptom Assessment; Time Factors; Viral Load; China
• ISSN: 0903-1936; 1399-3003; 1399-3003
• DOI: 10.1183/13993003.00763-2020

Timely diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a prerequisite for treatment and prevention. The serology characteristics and complement diagnosis value of the antibody test to RNA test need to be demonstrated. Serial sera of 80 patients with PCR-confirmed coronavirus disease 2019 (COVID-19) were collected at the First Affiliated Hospital of Zhejiang University, Hangzhou, China. Total antibody (Ab), IgM and IgG antibodies against SARS-CoV-2 were detected, and the antibody dynamics during the infection were described. The seroconversion rates for Ab, IgM and IgG were 98.8%, 93.8% and 93.8%, respectively. The first detectible serology marker was Ab, followed by IgM and IgG, with a median seroconversion time of 15, 18 and 20 days post exposure (d.p.e.) or 9, 10 and 12 days post onset (d.p.o.), respectively. The antibody levels increased rapidly beginning at 6 d.p.o. and were accompanied by a decline in viral load. For patients in the early stage of illness (0-7 d.p.o), Ab showed the highest sensitivity (64.1%) compared with IgM and IgG (33.3% for both; p<0.001). The sensitivities of Ab, IgM and IgG increased to 100%, 96.7% and 93.3%, respectively, 2 weeks later. When the same antibody type was detected, no significant difference was observed between enzyme-linked immunosorbent assays and other forms of immunoassays. A typical acute antibody response is induced during SARS-CoV-2 infection. Serology testing provides an important complement to RNA testing in the later stages of illness for pathogenic-specific diagnosis and helpful information to evaluate the adapted immunity status of patients.