Diagnosis of Acute Respiratory Syndrome Coronavirus 2 Infection by Detection of Nucleocapsid Protein

Bo Diao; Kun Wen; Jian Chen; Yueping Liu; Zilin Yuan; Chao Han; Jiahui Chen; Yuxian Pan; Li Chen; Yunjie Dan; Jing Wang; Yongwen Chen; Guohong Deng; Hongwei Zhou; Yuzhang Wu

Meanwhile, among the 31 patients with COVID-19 nucleic acid negative results, 31 were N antigen negative, with a specificity of 100%. In order to investigate the sensitivity and specificity of antigen detection methods from a clinical perspective, our study selected CT value ≤40 and ≤30 (Higher virus titer) as the nucleic acid positive group while CT value > 40 was used as the nucleic acid negative group. The results showed the positive coincidence rate (sensitivity) was 68%, the negative coincidence rate (specificity) was 100%,and the total coincidence rate (accuracy) was 72% when CT value≤40 as nucleic acid positive group while CT value > 40 as nucleic acid negative group (Fig3A). In addition, positive coincidence rate (sensitivity) was 98%, the negative coincidence rate (specificity) was 100%, and the total coincidence rate (accuracy) was 99% when CT value≤ 30 as nucleic acid positive group while CT value > 40 as nucleic acid negative group (Fig3B). It is of noteworthy that in this study cohort the earliest patient with fever in 3 days were identified by N antigen detection.