Head-to-head comparison of SARS-CoV-2 antigen-detecting rapid test with self-collected anterior nasal swab versus professional-collected nasopharyngeal swab

Abstract

Background: Two antigen-detecting rapid diagnostic tests (Ag-RDTs) are now approved through the WHO Emergency Use Listing procedure and can be performed at the point-of-care. However, both tests use nasopharyngeal (NP) swab samples. NP swab samples must be collected by trained healthcare personnel with protective equipment and are frequently perceived as uncomfortable by patients. Methods: This was a manufacturer-independent, prospective diagnostic accuracy study with comparison of a supervised, self-collected anterior nasal (AN) swab sample with a professional-collected NP swab sample, using a WHO-listed SARS-CoV-2 Ag-RDT, STANDARD Q COVID-19 Ag Test (SD Biosensor), which is also being distributed by Roche. The reference standard was RT-PCR from an oro-/nasopharyngeal swab sample. Percent positive and negative agreement as well as sensitivity and specificity were calculated. Results: Among the 289 participants, 39 (13.5%) tested positive for SARS-CoV-2 by RT-PCR. The positive percent agreement of the two different sampling techniques for the Ag-RDT was 90.6% (CI 75.8-96.8). The negative percent agreement was 99.2% (CI 97.2-99.8). The Ag-RDT with AN sampling showed a sensitivity of 74.4% (29/39 PCR positives detected; CI 58.9-85.4) and specificity of 99.2% (CI 97.1-99.8) compared to RT-PCR. The sensitivity with NP sampling was 79.5% (31/39 PCR positives detected; CI 64.5-89.2) and specificity was 99.6% (CI 97.8-100). In patients with high viral load (>7.0 log10 RNA SARS-CoV2/swab), the sensitivity of the Ag-RDT with AN sampling was 96% and 100% with NP sampling. Conclusion: Supervised self-sampling from the anterior nose is a reliable alternative to professional nasopharyngeal sampling using a WHO-listed SARS-CoV-2 Ag-RDT. Considering the ease-of-use of Ag-RDTs, self-sampling and potentially patient self-testing at home may be a future use case.

SARS-CoV-2 patient self-testing with an antigen-detecting rapid test: a head-to-head comparison with professional testing

“…Sensitivities obtained in the present study were comparable to those observed in recent independent validation studies for the same Ag-RDT applied at this testing facility (73.2% to 80.5%) [10,11]. The slightly higher sensitivities in this study are likely due to the higher number of patients with a high viral load (72.5% with ≥7.0 log10 SARS-CoV-2 RNA copies/ml, versus 48.8% and 64.1% in the prior studies).…”

Limits and Opportunities of SARS-CoV-2 Antigen Rapid Tests: An Experienced-Based Perspective

“…There were no controls delivered with the test devices by Roche and RapiGEN. (2,4,6,8) and negative controls (NCs) (1, 3, 5, 7) of four kits were performed, according to the manufacturer's protocol; (B) Controls of approach (A) were pooled and applied to the antigen tests by Roche (9,10) and RapiGEN (11,12). While the PC by Abbott also became positive with Roche (10), the BIOCREDIT test did not recognize the positive control (11).…”

“…During the review process of this manuscript, further studies were published that also investigated the utility of lateral flow antigen assays for the detection of SARS-CoV-2 and reported similar shortcomings in the overall performance of those assays. Lindner et al reported sensitivities of 74.4 to 79.5% in agreement with PCR assays, which meant that up to 25% positive cases were not detected by lateral flow assays [6]. Additionally, Weitzel and coworkers evaluated the usage of universal transport medium and its performance on lateral flow antigen devices [7], and revealed that sensitivities ranging from 16.7 to 85% depended on the subgroup of specimens tested.…”

Evaluation of a SARS-CoV-2 rapid antigen test: Potential to help reduce community spread?

“…Despite high specificity and sensitivity, rRT-PCR has a disadvantage in point of care testing, because it usually requires professional expertise, expensive reagents and specialized equipment. Therefore, alternative assays, such as rapid antigen detection tests, which can also detect the presence of the virus directly in respiratory samples, have been developed [ 4 ] and tested by different groups [ [10] , [11] , [12] , [13] , [14] ]. However, it is vital to determine the sensitivity, specificity of such tests relative to standard rRT-PCR in order to identify the ideal circumstances that their application would be beneficial.…”