Performance and Implementation Evaluation of the Abbott BinaxNOW Rapid Antigen Test in a High-Throughput Drive-Through Community Testing Site in Massachusetts

Abstract

Background: Rapid diagnostic tests (RDTs) for SARS-CoV-2 antigens (Ag) that can be performed at point-of-care (POC) can supplement molecular testing and help mitigate the COVID-19 pandemic. Deployment of an Ag RDT requires an understanding of its operational and performance characteristics under real-world conditions and in relevant subpopulations. We evaluated the Abbott BinaxNOW™ COVID-19 Ag Card in a high-throughput, drive-through, free community testing site in Massachusetts (MA) using anterior nasal (AN) swab RT-PCR for clinical testing. Methods: Individuals presenting for molecular testing in two of seven lanes were offered the opportunity to also receive BinaxNOW testing. Dual AN swabs were collected from symptomatic and asymptomatic children (≤ 18 years) and adults. BinaxNOW testing was performed in a testing pod with temperature/humidity monitoring. One individual performed testing and official result reporting for each test, but most tests had a second independent reading to assess inter-operator agreement. Positive BinaxNOW results were scored as faint, medium, or strong. Positive BinaxNOW results were reported to patients by phone and they were instructed to isolate pending RT-PCR results. The paired RT-PCR result was the reference for sensitivity and specificity calculations. Results: Of 2482 participants, 1380 adults and 928 children had paired RT-PCR/BinaxNOW results and complete symptom data. 974/1380 (71%) adults and 829/928 (89%) children were asymptomatic. BinaxNOW had 96.5% (95% confidence interval [CI] 90.0- 99.3) sensitivity and 100% (98.6-100.0) specificity in adults within 7 days of symptoms, and 84.6% (65.1-95.6) sensitivity and 100% (94.5-100.0) specificity in children within 7 days of symptoms. Sensitivity and specificity in asymptomatic adults were 70.2% (56.6-81.6) and 99.6% (98.9-99.9), respectively, and in asymptomatic children were 65.4% (55.6-74.4) and 99.0% (98.0-99.6), respectively. By cycle threshold (Ct) value cutoff, sensitivity in all subgroups combined (n=292 RT-PCR-positive individuals) was 99.3% with Ct ≤25, 95.8% with ≤30, and 81.2% with ≤35. Twelve false positive BinaxNOW results (out of 2308 tests) were observed; in all twelve, the test bands were faint but otherwise normal, and were noted by both readers. One invalid BinaxNOW result was identified. Inter-operator agreement (positive versus negative BinaxNOW result) was 100% (n = 2230/2230 double reads). Each operator was able to process 20 RDTs per hour. In a separate set of 30 specimens (from individuals with symptoms ≤7 days) run at temperatures below the manufacturer’s recommended range (46-58.5°F), sensitivity was 66.7% and specificity 95.2%. Conclusions: BinaxNOW had very high specificity in both adults and children and very high sensitivity in newly symptomatic adults. Overall, 95.8% sensitivity was observed with Ct ≤ 30. These data support public health recommendations for use of the BinaxNOW test in adults with symptoms for ≤7 days without RT-PCR confirmation. Excellent inter-operator agreement indicates that an individual can perform and read the BinaxNOW test alone. A skilled laboratorian can perform and read 20 tests per hour. Careful attention to temperature is critical.

Performance of SARS-CoV-2 rapid antigen test compared with real-time RT-PCR in asymptomatic individuals

“…To date, most of these validations were carried out in symptomatic individuals or using previously collected samples (Cerutti et al, 2020;Kruttgen et al, 2021;Porte et al, 2020;Weitzel et al, 2020;Yamayoshi et al, 2020). In contrast, onsite test validation studies in asymptomatic individuals, to support the use of RAT in mass testing and epidemiological surveillance, are limited (Jakobsen et al, 2021;Mina et al, 2020;Pollock et al, 2021;Schildgen et al, 2021;Toptan et al, 2021). This study performed a mass comparison of RAT and real-time RT-PCR test in asymptomatic individuals from a Chilean region.…”

Accuracy of the Mologic COVID-19 rapid antigen test: a prospective multi-centre analytical and clinical evaluation

“…In a study in the Netherlands, sensitivity and specificity were 84.9% (CI 79.1-89.4) and 99.5% (CI 98.7-99.8) among 970 symptomatic adults using the Ag-RDT Standard Q (SD Biosensor, Korea) 10 . A high throughput drive-through community testing site in Massachusetts found similar results of 84.1% (CI 77.4 -89.4) sensitivity and 99.6% (99.1 -99.9) of specificity among 1385 adults using the Ag-RDT kit Abbott Binax NOW (Abbot, US) 31 . Results of Ag-RDT in drive-through centres suggest that the use of these would provide a good method to identify the majority of infected people (>84%), enabling faster detection of infected cases and implementation strategies than with RT-qPCR.…”

Test it earlier, result it faster, makes us stronger: how rapid viral diagnostics enable therapeutic success

“…The limited analytical sensitivity of antigen testing fell out of favor after the 2009 H1N1 pandemic, when these tests had below 50% sensitivity for the novel reassortant influenza virus [ 36 , 37 ]. New antigen readers and rapid lateral flow technologies combined with specific development of reagents for SARS-CoV-2 and its comparably low genetic diversity brought more respectable analytical and clinical sensitivities for these assays, approaching Ct ∼30 or viral loads in the mid-tens of thousands of copies/mL [ 38 , 39 ]. Depending on whether antigen testing was performed on asymptomatic or early symptomatic individuals and when testing was performed relative to peak community transmission, clinical sensitivities of SARS-CoV-2 antigen testing could range from as low as 56–77% in asymptomatic to >96% in individuals in their first week of symptoms [ 39 , 40 , 41 , 42 ].…”

“…New antigen readers and rapid lateral flow technologies combined with specific development of reagents for SARS-CoV-2 and its comparably low genetic diversity brought more respectable analytical and clinical sensitivities for these assays, approaching Ct ∼30 or viral loads in the mid-tens of thousands of copies/mL [ 38 , 39 ]. Depending on whether antigen testing was performed on asymptomatic or early symptomatic individuals and when testing was performed relative to peak community transmission, clinical sensitivities of SARS-CoV-2 antigen testing could range from as low as 56–77% in asymptomatic to >96% in individuals in their first week of symptoms [ 39 , 40 , 41 , 42 ]. The success has led to a new FDA pathways for authorization of at-home, over the-counter, and/or serial rapid antigen testing, with multiple rapid antigen tests now authorized for over the-counter purchase that can be run at home.…”