Association of the Serum Levels of the Nucleocapsid Antigen of SARS-CoV-2 With the Diagnosis, Disease Severity, and Antibody Titers in Patients With COVID-19: A Retrospective Cross-Sectional Study

• DOI: 10.3389/fmicb.2021.791489
• Publication Date: 2021-12-09T13:06:50Z
• Authors: Rin Yokoyama; Makoto Kurano; Yuki Nakano; Yoshifumi Morita; Hiroko Ohmiya; Yoshiro Kishi; Jun Okada; Chungen Qian; Fuzhen Xia; Fan He; Liang Zheng; Yi Yu; Miyuki Mizoguchi; Yoshimi Higurashi; Sohei Harada; Daisuke Jubishi; Koh Okamoto; Kyoji Moriya; Tatsuhiko Kodama; Yutaka Yatomi
• Keywords: Clinical Significance; Youden's J statistic

Background: Several types of laboratory tests for COVID-19 have been established to date; however, the clinical significance serum SARS-CoV-2 nucleocapsid (N) antigen levels remains be fully elucidated. In present study, we attempted elucidate usefulness and N levels. Methods: We measured in 391 samples collected from symptomatic patients with a confirmed diagnosis 96 non-COVID-19, using automated chemiluminescence immunoassay analyzer. Results: Receiver operating characteristic analysis identified optimal cutoff value level (cutoff index, based on Youden's index) as 0.255, which yielded sensitivity specificity 91.0 81.3%, respectively. The were significantly higher patient groups moderate severe than mild disease. Moreover, significant negative correlation was observed between IgG antibody titers, especially COVID-19. Conclusion: Serum testing might useful both obtaining better understanding features