One Swab Fits All: Performance of a Rapid, Antigen-Based SARS-CoV-2 Test Using a Nasal Swab, Nasopharyngeal Swab for Nasal Collection, and RT–PCR Confirmation from Residual Extraction Buffer

Abstract

Background Point-of-care SARS-CoV-2 antigen tests have great potential to help combat the COVID-19 pandemic. In the performance of a rapid, antigen-based SARS-CoV-2 test (RAT), our study had 3 main objectives: to determine the accuracy of nasal swabs, the accuracy of using nasopharyngeal swabs for nasal collection (nasalNP), and the effectiveness of using residual extraction buffer for real-time reverse-transcriptase PCR (RT–PCR) confirmation of positive RAT (rPan). Methods Symptomatic adults recently diagnosed with COVID-19 in the community were recruited into the study. Nasal samples were collected using either a nasalNP or nasal swab and tested immediately with the RAT in the individual’s home by a health care provider. 500 µL of universal transport media was added to the residual extraction buffer after testing and sent to the laboratory for SARS-CoV-2 testing using RT–PCR. Parallel throat swabs tested with RT–PCR were used as the reference comparators. Results One hundred and fifty-five individuals were included in the study (99 nasal swabs, 56 nasalNP). Sensitivities of nasal samples tested on the RAT using either nasal or nasalNP were 89.0% [95% confidence interval (CI) 80.7%–94.6%] and 90.2% (95% CI 78.6%–96.7%), respectively. rPan positivity agreement compared to throat RT–PCR was 96.2%. Conclusions RAT reliably detect SARS-CoV-2 from symptomatic adults in the community presenting within 7 days of symptom onset using nasal swabs or nasalNP. High agreement with rPan can avoid the need for collecting a second swab for RT–PCR confirmation or testing of variants of concern from positive RAT in this population.

Nasal swab is a good alternative sample for detecting SARS-CoV-2 with rapid antigen test: A meta-analysis

“…Among the 49 studies on nasal swabs containing 79,073 samples [ [2] , [3] , [4] , 6 , [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] ], all of them were published between 2021 and 2022, and twenty-one studies were conducted in the USA [ 12 , 14 , 15 , 18 , 21 , 22 , [25] , [26] , [27] , [32] , [33] , [34] , [35] , 39 , 44 , 45 , [47] ...…”

Clinical Performance of Self-Collected Nasal Swabs and Antigen Rapid Tests for SARS-CoV-2 Detection in Resource-Poor Settings

“…Differences in study settings, population immunity, epidemiological context, and workload at health facilities could have caused some of the differences in assay performance observed in our study. Evaluations performed in clinical settings and populations from Canada, United Kingdom, United States, and Germany reported discrepant sensitivities [ 24 , 25 , 26 , 27 ]. For example, in United Kingdom, in ambulance services and walk-through testing settings, Cubas-Attienzar et al (2021) evaluated the COVIOS nasal antigen SARS-CoV-2 rapid tests and found a higher sensitivity and specificity, of 85.0% and 97.8%, respectively [ 26 ].…”

Adequacy of using a residual nasal swab specimen from a rapid influenza diagnostic test to perform PCR and whole genome sequencing

“…More recently, a study showed that the residual buffer left over from a rapid SARS-CoV-2 test could be used to confirm a positive result through RT-PCR. 9 Another study demonstrated that WGS could be performed on both residual nasal swabs and the positive line on a lateral flow assay. 8…”

“…The efficacy of using a residual nasal swab (rNS) for molecular testing, following preparation for and performance of rapid testing, is not well understood, but a couple studies have showed that a rNS may be sufficient for performing RT-PCR and WGS on prospective SARS-CoV-2 specimens. 8,9 To determine whether a single anterior nasal swab is sufficient for confirming rapid influenza diagnostic test (RIDT) results, we performed RT-PCR on paired NP/OP and rNS specimens collected from patients of all ages in primary care clinics. Additionally, we performed WGS on a subset of paired specimens.…”