AUTHOR=Deng Qiaoling , Ye Guangming , Pan Yunbao , Xie Wen , Yang Gui , Li Zhiqiang , Li Yirong 

TITLE=High Performance of SARS-Cov-2N Protein Antigen Chemiluminescence Immunoassay as Frontline Testing for Acute Phase COVID-19 Diagnosis: A Retrospective Cohort Study

JOURNAL=Frontiers in Medicine

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2021.676560

DOI=10.3389/fmed.2021.676560

ISSN=2296-858X

ABSTRACT=Disease COVID-19 emerged and rapidly spread throughout the world. Testing strategies focus on patients with COVID-19 requires assays that are high-throughput, low-risk of infection and small sample volumes. Antigen surveillance can be used to identify exposure to pathogens and measure acute infections.  A total of 862 serum samples collected from 309 currently infected COVID-19 patients, 48 recovered ones and 358 controls were used to measure N protein antigen by an electro-chemiluminescence-based assay. Seropositivity and diagnostic performances were analyzed in different periods after onset. 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 (0.13 COI). In receiver-operating characteristic curve analysis, 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 77.12% and 98.60%. Diagnosis performance of specific antibodies became better from third week after onset. Subgroup analysis suggested that severe patients had higher levels of antigens than mild patients. High level of serum antigen suggested early infection and seriously ill. Serology N protein antigen testing by electro-chemiluminescence was considered as a viable assay used to improve diagnostic sensitivity for currently patients.