Detection of antibodies against SARS-CoV-2 as a serologic marker of infection in patients with COVID-19 / 中国输血杂志
Chinese Journal of Blood Transfusion
; (12): 861-864, 2021.
Article
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| WPRIM
| ID: wpr-1004430
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ABSTRACT
【Objective】 To investigate the diagnostic value of severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) specific antibodies IgM and IgG on coronavirus disease 2019 (COVID-19). 【Methods】 1) The test results of SARS-CoV-2 IgM/IgG antibodies and nucleic acid(NAT), which were tested by colloidal gold test and fluorescent quantitative PCR respectively, were collected from 145 febrile outpatients during early March, 2020, named Fever group, in which retrospective analysis and paired chi-square test were performed. 2) 612 cases of SARS-CoV-2 IgM/IgG antibodies test results, which were done on March 5, 2020, were collected. They were named COVID-19 group (Our hospital was provisionally assigned as a specialized hospital for COVID-19, and 1500 COVID-19 patients admitted to our hospital from February 12, 2020 to March 18, 2020). The SARS-CoV-2 IgM/IgG antibodies and NAT were respectively tested on the 30th and the 60th day after the date of discharge. The clinical application values of the antibodies was clarified by statistical analysis. 【Results】 1) In the fever group, the positive rate of SARS-CoV-2 IgM, IgG and IgM+ IgG antibodies were 26.21% (38/145), 54.48% (79/145) and 26.21% (38/145), respectively(P<0.01), and the positive rate of NAT was 4.14% (6/145), which was lower than that of antibody (P<0.01). One (1/145, 0.69%) positive NAT was implicated in initially negative IgM and IgG antibodies samples. 2) In the COVID-19 group, the positive rate of IgM antibody was low (5%) and IgG antibody was high (65%) during 2~14 days after infection, and stably increased during the 15~56 days [IgM 47.68%(277/581) vs IgG 94.15% (547/581) ], then both decreased after 57 days. The positive rates of IgM antibody and IgG antibody were 45.8% (280/612) and 93.1% (570/612) in 612 patients during hospitalization. 15 patients′ data after dischange were not collected as they were later transferred to Huoshenshan Hospital for treatment. The coronavirus NAT results of the rest 597 COVID-19 patients, tested on the 30th and 60th days after the date of discharge, were negative, and the positive rates of IgG antibody and IgM antibody were still ≥80% and ≥40% respectively at the second month after discharge. 【Conclusion】 IgM, IgG antibody against SARS-CoV-2 can be well detected by Colloidal gold method(Innovita), whose positive rate is higher than that of NAT. IgG antibody is produced earlier than IgM, and it keeps high positive rate and persists for a long time. The combination of colloidal gold antibody test and NAT can improve the diagnose rate of COVID-19 and the exclusion of suspected cases.