Objective  To compare the significance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid and antibody detection for diagnosis of the virus infection.

  Methods   Totally 192 serum samples and 192 nasopharyngeal swab specimens (33 negative and 159 positive for SARS-CoV-2) were collected from 68 confirmed corona-virus disease 2019 (COVID-19) cases and their close contacts and 91 attendees of fever clinics at medical institutions or centralized quarantine sites in Wuxi city of Jiangsu province between January 25 and February12, 2020. The swab specimens were detected for SARS-CoV-2 nucleic acid with fluorescence-based real-time reverse transcription PCR (RT-PCR) and the serum samples were detected for immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies of SARS-CoV-2 with colloidal gold method retrospectively.

  Results  The positive rate of SARS-CoV-2 nucleic acid was 17.19% (33/192) for the swab specimens; for the serum samples, the antibody-positive rates were 7.29% (14/192) for IgM, 11.46% (22/192) for IgG, and 11.46% (22/192) for either IgM or IgG, respectively. The results of Kappa test indicated a good consistency between detections of viral nucleic acid and IgM, IgG and IgM/IgG, with the Kappa values of 0.502, 0.726 and 0.726 (all P < 0.001). The total compliance rate of the two detection methods was 93.23% (179/192).With the RT-PCR results of swab specimen viral nucleic acid as the gold standard, the indicators of colloidal gold serum IgM/IgG antibody detection for SARS-CoV-2 infection were 63.64% for sensitivity, 99.37% for specificity, 95.45% for positive predictive value, 92.94% for negative predictive value, and 63.01% for accuracy, respectively.

  Conclusion   Colloidal gold detection of serum IgM and IgG antibody is of convenience, rapidity, high sensitivity and specificity in the screening of SARS-CoV-2 infection and could be used as a supplementary detection among viral nucleic acid negative cases in RT-PCR test. The combined application of the two detections may play an important role in the diagnosis, prevention and control of COVID-19.