A comparative analysis of nucleic acid detection and specific IgM antibody detection in the diagnosis of novel coronavirus

Objective To compare real-time fluorescence quantitative RT-PCT and fluorescence immunochromatography for detection of the nucleic acid of novel coronavirus (SARS-CoV-2), so as to provide reference for the diagnosis of corona virus disease 2019 (COVID-19). Methods A total of 82 suspected COVID-19 patients were selected. Their positive rates of SARS-CoV-2 nucleic acid in nasopharyngeal swab samples and IgM antibody in whole blood samples were detected from the day when clinical symptoms appeared until 21 days later. Meanwhile, 50 medical staff without COVID-19 in Dongtan People's Hospital were selected as a control group. Results Based on nucleic acid detection method, 74 SARS-CoV-2 positive cases were found in the COVID-19 suspected patient group, with a positive rate of 90.24%, while there was one temporarily positive case in the control group, with a positive rate of 2.00%. Based on IgM antibody detection method, 66 SARS-CoV-2 cases were detected in the COVID-19 suspected patient group, with a positive rate of 80.49%, while all the samples were negative in the control group. The detection time of nucleic acid was from Days 1 to 18, reaching a peak from Days 1 to 8. The detection time of IgM antibody was from Days 3 to 19, reaching a peak from Days 5 to 14. Conclusions The peak period of IgM antibody detection is about one week behind the peak period of nucleic acid detection. Both methods are complementary, which is of importance to diagnose COVID-19 with a detoxification volume less than the nucleic acid concentration threshold. It is more reliable to use both nucleic acid and serological detection methods for COVID-19 diagnosis.