The Value of Rapid Antigen Tests for Identifying Carriers of Viable SARS-CoV-2

Abstract

The search for effective methods to detect patients who excrete a viable virus is one of the urgent tasks of modern biomedicine. In the present study, we examined the diagnostic value of two antigen tests, BIOCREDIT COVID-19 Ag (RapiGEN Inc., Anyang, Korea) and SGTI-flex COVID-19 Ag (Sugentech Inc., Cheongju, Korea), for their diagnostic value in identifying patients who excrete viable SARS-CoV-2. As part of the study, we examined samples from 106 patients who had just been admitted to the hospital and who had undergone quantitative RT-PCR and assessment of viability of SARS-CoV-2 using cell culture. Assessment of the tests’ value for detecting samples containing viable virus showed high sensitivity for both tests. Sensitivity was 78.6% (95% CI, from 49.2% to 95.3%) for SGTI-flex COVID-19 Ag and 100% (95% CI, from 76.8% to 100%) for Biocredit COVID-19 Ag. The specificity of rapid tests was significantly higher than that of RT-PCR and was 66.3% (95% CI, from 55.7% to 75.8%) and 67.4% (95% CI, from 56.8% to 76.8%) for SGTI-flex COVID-19 Ag and Biocredit COVID-19 Ag versus 30.4% (95% CI, from 21.3% to 40.9%) obtained for PCR. Thus, for tasks of identifying viable SARS-CoV-2 during screening of conditionally healthy people, as well as monitoring those quarantined, rapid tests show significantly better results.

A Protein Microarray-Based Respiratory Viral Antigen Testing Platform for COVID-19 Surveillance

“…The LoD was calculated rather stringently by multiplying 3.3 to the standard deviation of the y-intercept over the slope, which was determined to be 1.54 × 10 5 TCID 50 /mL. This LoD is generally comparable to those obtained from other SARS-CoV-2 antigen tests [ 39 , 40 , 41 ]. In addition, the heat inactivation of the SARS-CoV-2 samples decreases the virus titer up to 4 Log10 in TCID 50 [ 42 ], which affected the antigen detection on the protein microarray and therefore the LoD calculation.…”

“…Specifically, our antibody microarray-based SARS-CoV-2 antigen test exhibited the clinical sensitivity and specificity of 77.2% and 100%, respectively, which are comparable to existing SARS-CoV-2 antigen tests [ 34 , 44 ]. Of note, we demonstrate the microarray assay correlates well with RT-PCR Ct values and is particularly effective in identifying high viral titers (i.e., low Ct values) that have shown to associate with infectivity and transmission [ 39 , 48 , 49 ]. However, although our clinical sensitivity matches to some of literature values, such as other antigen tests, our assay design would be challenging to detect early and asymptomatic COVID-19 patients [ 7 ].…”

Lithographic SERS Aptasensor for Ultrasensitive Detection of SARS-CoV-2 in Biological Fluids

“…According to the measurement results, the given sensor enables the detection of SARS-CoV-2 with a sensitivity of 100 copies/mL, which is comparable to the limit of detection for the polymerase chain reaction, LOD = 10 2 –10 3 copies/mL [ 20 , 21 ]. Thus, the experimental evidence demonstrates that the proposed sensor is superior in sensitivity to the rapid antibody-based assays (LOD = 10 6 copies/mL) [ 22 ].…”

Prospective Clinical Evaluation of the Diagnostic Accuracy of a Highly Sensitive Rapid Antigen Test Using Silver Amplification Technology for Emerging SARS-CoV-2 Variants

“…In many cases, replicative SARS-CoV-2 cannot be isolated from specimens with Ct values above 30, suggesting that the threshold for infectivity and transmissibility of SARS-CoV-2 corresponds with the Ct value of 30 [ 18 , 19 ]. The prompt identification of carriers of viable SARS-CoV-2 and the prevention of secondary infections and clusters is the most important step in controlling a local epidemic [ 20 ]. Therefore, detecting cases of viral infection corresponding with a Ct value ≤30 is important.…”