In this study, we aimed to evaluate the diagnostic value of serological assay for SARS-CoV-2. A newly-developed ELISA assay for IgM and IgG antibodies against N protein of SARS-CoV-2 was used to screen the serums of 238 admitted hospital patients between February 6 and February 14, 2020 with confirmed or suspected SARS-CoV-2. SARS-CoV-2 RNA was detected on pharyngeal swab specimens using real time RT-PCR. 194 (81.5%) of the serums were detected to be antibody (IgM and/or IgG) positive, significantly higher than the positive rate of viral RNA (64.3%). There was no difference in the positive rate of antibodies between the confirmed patients (83.0%, 127/153) and the suspected patients (78.8%, 67/85), whose nucleic acid tests were negative. The antibody positive rates were very low in the first five days after initial onset of symptoms, and then rapidly increased as the disease progressed. After 10 days, the antibody positive rates jumped from below 50% to over 80%. However, the positive rates of viral RNA maintained above 60% in the first 11 days after initial onset of symptoms, and then rapidly decreased. Overall, the suspected patients were most likely infected by SARS-CoV-2. Before the 11th day after initial onset of symptoms, nucleic acid test is key for confirmation of viral infection. The combination of serological assay can greatly improve the diagnostic efficacy. After the 11th day post-disease onset, the diagnosis for viral infection should be majorly dependent on serological assay.

在这项研究中，我们旨在评估血清学检测对SARS-CoV-2的诊断价值。一项针对SARS-CoV-2 N蛋白的IgM和IgG抗体的新开发的ELISA检测方法用于筛选2020年2月6日至2月14日之间确诊或怀疑为SARS-CoV-2的238例入院患者的血清。使用实时RT-PCR在咽拭子标本上检测到SARS-CoV-2 RNA。经检测，有194个（81.5％）血清为抗体（IgM和/或IgG）阳性，显着高于病毒RNA的阳性率（64.3％）。在确诊的患者（83.0％，127/153）和怀疑的患者（78.8％，67/85）之间，抗体的阳性率没有差异，这些患者的核酸检测结果均为阴性。在最初出现症状后的头五天内，抗体阳性率非常低，然后随着疾病的发展而迅速增加。10天后，抗体阳性率从低于50％跃升至超过80％。但是，病毒RNA的阳性率在症状最初发作后的头11天保持在60％以上，然后迅速下降。总体而言，可疑患者最有可能感染SARS-CoV-2。在症状首次发作后的第11天之前，核酸测试是确认病毒感染的关键。血清学检测的结合可以大大提高诊断效率。疾病发作后第11天后，病毒感染的诊断应主要取决于血清学检测。症状最初发作后的头11天，病毒RNA的阳性率保持在60％以上，然后迅速下降。总体而言，可疑患者最有可能感染SARS-CoV-2。在症状首次发作后的第11天之前，核酸测试是确认病毒感染的关键。血清学检测的结合可以大大提高诊断效率。疾病发作后第11天后，病毒感染的诊断应主要取决于血清学检测。症状最初发作后的头11天，病毒RNA的阳性率保持在60％以上，然后迅速下降。总体而言，可疑患者最有可能感染SARS-CoV-2。在症状首次发作后的第11天之前，核酸测试是确认病毒感染的关键。血清学检测的结合可以大大提高诊断效率。疾病发作后第11天后，病毒感染的诊断应主要取决于血清学检测。血清学检测的结合可以大大提高诊断效率。疾病发作后第11天后，病毒感染的诊断应主要取决于血清学检测。血清学检测的结合可以大大提高诊断效率。疾病发作后第11天后，病毒感染的诊断应主要取决于血清学检测。