Objectives: COVID-19 emerged and rapidly spread throughout the world. Testing strategies focussing on patients with COVID-19 require assays that are high-throughput, low-risk of infection, and with small sample volumes. Antigen surveillance can be used to identify exposure to pathogens and measure acute infections. Methods: A total of 914 serum samples, collected from 309 currently infected COVID-19 patients, 48 recovered ones, and 410 non-COVID-19 patients, were used to measure N protein antigen levels by a chemilumineseent immunoassay. Diagnostic performances were analyzed in different periods after onset. Results: There was a high level of N protein antigen in COVID-19 patients (0.56 COI), comparing to the recovered patients (0.12 COI) and controls (0.19 COI). In receiver-operating characteristic curve analysis, the area under the curve of serum N protein antigen was 0.911 in the first week after onset. In this period, Sensitivity and specificity of serologic N protein antigen testing was 76.27 and 98.78%. Diagnosis performance of specific antibodies became better from the third week after onset. Subgroup analysis suggested that severe patients had higher levels of antigens than mild patients. Conclusions: High level of serum antigen suggested early infection and serious illness. Serum N protein antigen testing by chemiluminescence immunoassay is considered as a viable assay used to improve diagnostic sensitivity for current patients.
【저자키워드】 COVID-19, chemiluminescence immunoassay, testing strategies, SARS-CoV-2N protein antigen, diagnostic performances, 【초록키워드】 Infection, diagnostic, Antigen, Spread, immunoassay, serum, sensitivity, specificity, Testing, pathogen, Surveillance, N protein, Control, Severe patient, characteristic, patients, COVID-19 patients, mild patients, Analysis, early infection, COVID-19 patient, Non-COVID-19 patients, serum samples, acute infections, IMPROVE, recovered patient, analyzed, identify, collected, specific antibody, can be used, were used, suggested, patients with COVID-19, 【제목키워드】 Testing, performance, phase,