Performance of a novel diagnostic assay for rapid SARS-CoV-2 antigen detection in nasopharynx samples

Liotti, Flora Marzia; Menchinelli, Giulia; Lalle, Eleonora; Palucci, Ivana; Marchetti, Simona; Colavita, Francesca; Sorda, Marilena La; Sberna, Giuseppe; Bordi, Licia; Sanguinetti, Maurizio; Cattani, Paola; Capobianchi, Maria Rosaria

doi:10.1016/j.cmi.2020.09.030

Cited by 80 publications

(68 citation statements)

References 4 publications

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“…As recently highlighted by a systematic literature review published by the Cochrane COVID-19 Diagnostic Test Accuracy Group [7], the diagnostic sensitivity of many of these POC antigen SARS-CoV-2 tests seems acceptable in respiratory specimens with high viral load (e.g., typically >80% with cycle thresholds of 25 or lower), whilst the positive rate in samples with low viral load (e.g., cycle thresholds >25/30) is always <80%, being observed between 8 and 72%. This data was confirmed by another recent investigation published by Liotti et al [8], showing that the percent positivity agreement with NAATs of a commercially available rapid antigen test is >95% in upper respiratory tract specimens with high viral load (i.e., cycle thresholds <25), but dramatically declines to 20-40% in samples with cycle thresholds ≥25. Similar evidence has also been published by Porte and colleagues [9], who also found that the diagnostic sensitivity of a rapid antigen test was almost dependent on viral load (i.e., 100% in nasopharyngeal samples with cycle thresholds ≤25.1 vs. 72% in those with cycle thresholds >25.1), as well as by Nalumansi et al, who also showed that rapid antigen test results were more frequently positive in nasopharyngeal swabs with lower cycle thresholds (i.e., 92% with cycle thresholds ≤29 vs. 55% with cycle thresholds >29) [10].…”

Section: State Of the Art Of Rapid Antigen Tests For Sars-cov-2 Diagnsupporting

confidence: 73%

Making sense of rapid antigen testing in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostics

Mattiuzzi¹,

Henry

Lippi

2020

Diagnosis

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Although the most effective strategy for preventing or containing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks relies on early diagnosis, the paramount and unprecedented number of tests needed to fully achieve this target is overwhelming worldwide testing supply and capacity. Molecular detection of SARS-CoV-2 RNA in nasopharyngeal swabs is still considered the reference diagnostic approach. Nonetheless, identification of SARS-CoV-2 proteins in upper respiratory tract specimens and/or saliva by means of rapid (antigen) immunoassays is emerging as a promising screening approach. These tests have some advantages compared to molecular analysis, such as point of care availability, no need of skilled personnel and dedicated instrumentation, lower costs and short turnaround time. However, these advantages are counterbalanced by lower diagnostic sensitivity compared to molecular testing, which would only enable to identifying patients with higher SARS-CoV-2 viral load. The evidence accumulated to-date has hence persuaded us to develop a tentative algorithm, which would magnify the potential benefits of rapid antigen testing in SARS-CoV-2 diagnostics.

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Section: State Of the Art Of Rapid Antigen Tests For Sars-cov-2 Diagnsupporting

confidence: 73%

Making sense of rapid antigen testing in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostics

Mattiuzzi¹,

Henry

Lippi

2020

Diagnosis

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“…Such assays have recently been developed and brought to market by several manufacturers. However, so far there have been few independent studies evaluating their performance [ 9 , 10 , 11 , 12 , 13 , 14 ].…”

Section: Discussionmentioning

confidence: 99%

“…Thus, easy-to-perform lateral flow assays that can be applied for rapid detection of SARS-CoV-2 antigen at the point-of-care (POCT) may be useful to deal with these limitations. However, so far only a few studies on the diagnostic performance of such tests are available [ 9 , 10 , 11 , 12 , 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Performance of a Point-of-Care Test for the Rapid Detection of SARS-CoV-2 Antigen

Strömer

Rose

Schäfer³

et al. 2020

Microorganisms

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The rapid detection of infections caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is necessary in the ongoing pandemic. Antigen-specific point-of-care tests (POCT) may be useful for this purpose. Here, such a POCT (SARS-CoV-2 NADAL® COVID-19 Ag) was compared to a laboratory-developed triplex real-time polymerase chain reaction (RT-PCR) designed for the detection of viral nucleoprotein gene and two control targets. This RT-PCR served as a reference to investigate POCT sensitivity by re-testing upper respiratory tract (URT) samples (n = 124) exhibiting different SARS-CoV-2 loads in terms of RT-PCR threshold cycle (Ct) values. The optical intensities of the antigen bands were compared to the Ct values of the RT-PCR. The infectivity of various virus loads was estimated by inoculating Vero cells with URT samples (n = 64, Ct 17-34). POCT sensitivity varied from 100% (Ct < 25) to 73.1% (Ct ≤ 30); higher SARS-CoV-2 loads correlated with higher band intensities. All samples with a Ct > 30 were negative; among SARS-CoV-2 free samples (n = 10) no false-positives were detected. A head-to-head comparison with another POCT (Abbott, Panbio™ COVID-19 Ag Rapid Test) yielded similar results. Isolation of SARS-CoV-2 in cell-culture was successful up to a Ct value of 29. The POCT reliably detects high SARS-CoV-2 loads and rapidly identifies infectious individuals.

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“…Head-to-head comparisons of AD test performance for SARS-CoV-2 detection are scarce. The majority of the studies only included few patients, precluding a wide characterization of the “real-life” performance of these devices [ 3 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. Recently, a Cochrane study found an average sensitivity of only 56.2% (95% confidence interval (CI): 29.5–79.8%) for rapid AD (RAD) tests [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Head-to-Head Comparison of Rapid and Automated Antigen Detection Tests for the Diagnosis of SARS-CoV-2 Infection

Favresse

Gillot

Oliveira

et al. 2021

JCM

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(1) Background: The detection of SARS-CoV-2 RNA in nasopharyngeal samples through real-time reverse transcription-polymerase chain reaction (RT-PCR) is considered the standard gold method for the diagnosis of SARS-CoV-2 infection. Antigen detection (AD) tests are more rapid, less laborious, and less expensive alternatives but still require clinical validation. (2) Methods: This study compared the clinical performance of five AD tests, including four rapid AD (RAD) tests (biotical, Panbio, Healgen, and Roche) and one automated AD test (VITROS). For that purpose, 118 (62.8%) symptomatic patients and 70 (37.2%) asymptomatic subjects were tested, and results were compared to RT-PCR. (3) Results: The performance of the RAD tests was modest and allowed us to identify RT-PCR positive patients with higher viral loads. For Ct values ≤25, the sensitivity ranged from 93.1% (95% CI: 83.3–98.1%) to 96.6% (95% CI: 88.1–99.6%), meaning that some samples with high viral loads were missed. Considering the Ct value proposed by the CDC for contagiousness (i.e., Ct values ≤33) sensitivities ranged from 76.2% (95% CI: 65.4–85.1%) to 88.8% (95% CI: 79.7–94.7%) while the specificity ranged from 96.3% (95% CI: 90.8–99.0%) to 99.1% (95% CI: 95.0–100%). The VITROS automated assay showed a 100% (95% CI: 95.5–100%) sensitivity for Ct values ≤33, and had a specificity of 100% (95% CI: 96.6–100%); (4) Conclusions: Compared to RAD tests, the VITROS assay fully aligned with RT-PCR for Ct values up to 33, which might allow a faster, easier and cheaper identification of SARS-CoV-2 contagious patients.

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Performance of a novel diagnostic assay for rapid SARS-CoV-2 antigen detection in nasopharynx samples

Cited by 80 publications

References 4 publications

Making sense of rapid antigen testing in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostics

Making sense of rapid antigen testing in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostics

Performance of a Point-of-Care Test for the Rapid Detection of SARS-CoV-2 Antigen

Head-to-Head Comparison of Rapid and Automated Antigen Detection Tests for the Diagnosis of SARS-CoV-2 Infection

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