Comparison of automated SARS CoV 2 antigen test for COVID 19 infection with quantitative RT PCR using 313 nasopharyngeal swabs, including from seven serially followed patients
Abstract Severe acute respiratory syndrome coronavirus 2 (SARS CoV 2) infection is determined by reverse transcription PCR (RT PCR) in routine clinical practice. In the current pandemic situation, a more rapid and high throughput method is in growing demand. Here, we validated the performance of a new antigen test (LUMIPULSE) based on the chemiluminescence enzyme immunoassay. A total of 313 nasopharyngeal swabs (82 serial samples from 7 infected patients, 231 individual samples from 4 infected patients and 215 non infected individuals) were analyzed for SARS CoV 2 by quantitative RT PCR (RT qPCR) and then subjected to LUMIPULSE. We determined the cutoff value for antigen detection using receiver operating characteristic curve analysis and compared the antigen test performance with that of RT qPCR. Further, we compared the viral loads and antigen levels in serial samples from seven infected patients. When using RT qPCR as the reference, the antigen test exhibited 55.2% sensitivity and 99.6% specificity with a 91.4% overall agreement rate (286/313) In specimens with 100 viral copies and between 10 and 100 copies, the antigen test showed 100% and 85% concordance with RT qPCR, respectively. This concordance declined with lower viral loads. In the serially followed patients, the antigen levels showed a steady decline along with viral clearance. This gradual decline was in contrast with the abrupt "positive to negative" and "negative to positive" status changes observed with RT qPCR, particularly in the late phase of infection. In summary, the LUMIPULSE antigen test can rapidly identify SARS CoV 2 infected individuals with moderate to high viral loads and may be helpful for monitoring viral clearance in hospitalized patients.
International Journal of Infectious Diseases