Time course of the sensitivity and specificity of anti-SARS-CoV-2 IgM and IgG antibodies for symptomatic COVID-19 in Japan

• Published in: Scientific reports Vol. 11; no. 1; pp. 2776 - 10
• Main Authors: Nakano, Yuki, Kurano, Makoto, Morita, Yoshifumi, Shimura, Takuya, Yokoyama, Rin, Qian, Chungen, Xia, Fuzhen, He, Fan, Kishi, Yoshiro, Okada, Jun, Yoshikawa, Naoyuki, Nagura, Yutaka, Okazaki, Hitoshi, Moriya, Kyoji, Seto, Yasuyuki, Kodama, Tatsuhiko, Yatomi, Yutaka
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 02.02.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 692/53/2421; 692/699/255; Antibody Specificity; Chemiluminescence; Coronaviridae; Coronaviruses; COVID-19; COVID-19 - immunology; COVID-19 - virology; COVID-19 Testing; Diagnosis; Enzyme-Linked Immunosorbent Assay; Humanities and Social Sciences; Humans; Immunoglobulin G; Immunoglobulin G - immunology; Immunoglobulin M; Immunoglobulin M - immunology; Japan; multidisciplinary; Nucleocapsids; SARS-CoV-2 - immunology; Science; Science (multidisciplinary); Sensitivity analysis; Severe acute respiratory syndrome coronavirus 2; Spike protein; Japan
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-82428-5

The accurate and prompt diagnosis of SARS-CoV-2 infection is required for the control and treatment of the coronavirus infection disease 2019 (COVID-19). In this study, we aimed to investigate the time courses of the anti-severe acute corona respiratory syndrome coronavirus 2 (SARS-CoV-2) IgM and IgG titers and to evaluate the sensitivity and specificity of such tests according to the specific day after the onset of COVID-19 among a patient population in Japan. We measured the titers of SARS-CoV-2 IgM and IgG in sera from 105 subjects, including 26 symptomatic COVID-19 patients, using chemiluminescent immunoassay (CLIA) methods utilizing magnetic beads coated with SARS-CoV-2 nucleocapsid protein and spike protein. The results of a ROC analysis suggested the possibility that the cutoff values in Japan might be lower than the manufacturer’s reported cutoff (10 AU/mL): 1  AU/mL for IgM and 5  AU/mL for IgG. The sensitivity of the test before Day 8 after symptom onset was less than 50%; at Days 9–10, however, we obtained a much higher sensitivity of 81.8% for both IgM and IgG. At 15 days or later after symptom onset, the SARS-CoV-2 IgG test had a sensitivity of 100%. These results suggest that if the number of days since disease onset is taken into consideration, these antibody tests could be very useful for the diagnosis of COVID-19 and similar diseases.