scholarly journals Performance of antigen testing for diagnosis of COVID-19: a direct comparison of a lateral flow device to nucleic acid amplification based tests

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Maria Kahn ◽  
Lukas Schuierer ◽  
Christina Bartenschlager ◽  
Stephan Zellmer ◽  
Ramona Frey ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Real Life ◽  
Lateral Flow ◽  
Nucleic Acid Amplification ◽  
University Hospital ◽  
Nasopharyngeal Swab ◽  
Screening Programs ◽  
Asymptomatic Patients ◽  
Antigen Tests ◽  
Antigen Testing

Abstract Objectives The gold standard for diagnosing an infection with SARS-CoV-2 is detection of viral RNA by nucleic acid amplification techniques. Test capacities, however, are limited. Therefore, numerous easy-to-use rapid antigen tests based on lateral flow technology have been developed. Manufacturer-reported performance data seem convincing, but real-world data are missing. Methods We retrospectively analysed all prospectively collected antigen tests results performed between 23.06.2020 and 26.11.2020, generated by non-laboratory personnel at the point-of-care from oro- or nasopharyngeal swab samples at the University Hospital Augsburg and compared them to concomitantly (within 24 h.) generated results from molecular tests. Results For a total of 3630 antigen tests, 3110 NAAT results were available. Overall, sensitivity, specificity, NPV and PPV of antigen testing were 59.4%, 99.0%, 98.7% and 64.8%, respectively. Sensitivity and PPV were lower in asymptomatic patients (47.6% and 44.4%, respectively) and only slightly higher in patients with clinical symptoms (66.7% and 85.0%, respectively). Some samples with very low Ct-values (minimum Ct 13) were not detected by antigen testing. 31 false positive results occurred. ROC curve analysis showed that reducing the COI cut-off from 1, as suggested by the manufacturer, to 0.9 is optimal, albeit with an AUC of only 0.66. Conclusion In real life, performance of lateral-flow-based antigen tests are well below the manufacturer's specifications, irrespective of patient’s symptoms. Their use for detection of individual patients infected with SARS-CoV2 should be discouraged. This does not preclude their usefulness in large-scale screening programs to reduce transmission events on a population-wide scale.

scholarly journals Quantitative Comparison of SARS-CoV-2 Nucleic Acid Amplification Test and Antigen Testing Algorithms: A Decision Analysis Simulation Model

2021 ◽  
Author(s):  
Phillip P. Salvatore ◽  
Melisa M. Shah ◽  
Laura Ford ◽  
Augustina Delaney ◽  
Christopher H. Hsu ◽  
...  
Keyword(s):  
Public Health ◽  
Nucleic Acid ◽  
Decision Analysis ◽  
Quantitative Comparison ◽  
Nucleic Acid Amplification ◽  
Infection Prevalence ◽  
Health Organizations ◽  
Public Health Organizations ◽  
Antigen Tests ◽  
Antigen Testing

AbstractBackgroundAntigen tests for SARS-CoV-2 offer advantages over nucleic acid amplification tests (NAATs, such as RT-PCR), including lower cost and rapid return of results, but show reduced sensitivity. Public health organizations continue to recommend different strategies for utilizing NAATs and antigen tests in various settings. There has not yet been a quantitative comparison of the expected performance of these strategies.MethodsWe utilized a decision analysis approach to simulate the expected outcomes of six algorithms for implementing NAAT and antigen testing, analogous to testing strategies recommended by public health organizations. Each algorithm was simulated 50,000 times for four SARS-CoV-2 infection prevalence levels ranging from 5% to 20% in a population of 100000 persons seeking testing. Primary outcomes were number of missed cases, number of false-positive diagnoses, and total test volumes. Outcome medians and 95% uncertainty ranges (URs) were reported.ResultsAlgorithms that use NAATs to confirm all negative antigen results minimized missed cases but required high NAAT capacity: 92,200 (95% UR: 91,200-93,200) tests (in addition to 100,000 antigen tests) at 10% prevalence. Substituting repeat antigen testing in lieu of NAAT confirmation of all initial negative antigen tests resulted in 2,280 missed cases (95% UR: 1,507-3,067) at 10% prevalence. Selective use of NAATs to confirm antigen results when discordant with symptom status (e.g., symptomatic persons with negative antigen results) resulted in the most efficient use of NAATs, with 25 NAATs (95% UR: 13-57) needed to detect one additional case at 10% prevalence compared to exclusive use of antigen tests.ConclusionsNo single SARS-CoV-2 testing algorithm is likely to be optimal across settings with different levels of prevalence and for all programmatic priorities; each presents a trade-off between prioritized outcomes and resource constraints. This analysis provides a framework for selecting setting-specific strategies to achieve acceptable balances and trade-offs between programmatic priorities and constraints.DisclaimerThe findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the U.S. Centers for Disease Control and Prevention.

scholarly journals SARS-CoV-2 Antigen Tests Predict Infectivity Based on Viral Culture: Comparison of Antigen, PCR Viral Load, and Viral Culture Testing on a Large Sample Cohort

2021 ◽  
Author(s):  
James E Kirby ◽  
Stefan Riedel ◽  
Sanjucta Dutta ◽  
Ramy Arnaout ◽  
Annie Cheng ◽  
...  
Keyword(s):  
Viral Load ◽  
Diagnostic Testing ◽  
Lateral Flow ◽  
Nasopharyngeal Swab ◽  
Viral Culture ◽  
Culture Positivity ◽  
Antigen Tests ◽  
Relationship Of ◽  
The Relationship ◽  
Antigen Testing

The relationship of SARS-CoV-2 antigen testing results, viral load, and viral culture detection remains to be fully defined. Presumptively, viral culture can provide a surrogate measure for infectivity of sampled individuals, and thereby inform how and where to most appropriately deploy available diagnostic testing modalities. We therefore determined the relationship of antigen testing results from three lateral flow and one microfluidics assay to viral culture performed in parallel in 181 nasopharyngeal swab samples positive for SARS-CoV-2. Sample viral loads, determined by RT-qPCR, were distributed across the range of viral load values observed in our testing population. We found that antigen tests were predictive of viral culture positivity, with the LumiraDx method showing enhanced sensitivity (90%; 95% confidence interval (95% CI) 83-94%) compared with the BD Veritor (74%, 95% CI 65-81%), CareStart (74%, 95% CI 65-81%) and Oscar Corona (74%, 95% CI 65-82%) lateral flow antigen tests. Antigen and viral culture positivity were also highly correlated with sample viral load, with areas under the receiver?operator characteristic curves (ROCs) of 0.94-0.97 and 0.92, respectively. In particular, a viral load threshold of 100,000 copies/mL was 95% sensitive (95% CI, 90-98%) and 72% specific (95% CI, 60-81%) for predicting viral culture positivity. Taken together, the detection of SARS-CoV-2 antigen identified highly infectious individuals, some of whom may harbor 10,000-fold more virus in their samples than those with any detectable infectious virus. As such, our data support use of antigen testing in defining infectivity status at the time of sampling.

scholarly journals Implementing SARS-CoV-2 Rapid Antigen Testing in the Emergency Ward of a Swiss University Hospital: The INCREASE Study

2021 ◽  
Vol 9 (4) ◽  
pp. 798
Author(s):  
Giorgia Caruana ◽  
Antony Croxatto ◽  
Eleftheria Kampouri ◽  
Antonios Kritikos ◽  
Onya Opota ◽  
...  
Keyword(s):  
Immunoglobulin A ◽  
University Hospital ◽  
Lower Sensitivity ◽  
Clinical Settings ◽  
Rt Pcr ◽  
Emergency Ward ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Asymptomatic Subjects ◽  
Antigen Testing

Following the Swiss Federal Office of Public Health (FOPH) authorization of the rapid antigen test (RAT), we implemented the use of the RAT in the emergency ward of our university hospital for patients’ cohorting. RAT triaging in association with RT-PCR allowed us to promptly isolate positive patients and save resources. Among 532 patients, overall sensitivities were 48.3% for Exdia and 41.2% for Standard Q®, PanbioTM and BD Veritor™. All RATs exhibited specificity above 99%. Sensitivity increased to 74.6%, 66.2%, 66.2% and 64.8% for Exdia, Standard Q®, PanbioTM and BD Veritor™, respectively, for viral loads above 105 copies/mL, to 100%, 97.8%, 96.6% and 95.6% for viral loads above 106 copies/mL and 100% for viral loads above 107 copies/mL. Sensitivity was significantly higher for patients with symptoms onset within four days (74.3%, 69.2%, 69.2% and 64%, respectively) versus patients with the evolution of symptoms longer than four days (36.8%, 21.1%, 21.1% and 23.7%, respectively). Among COVID-19 asymptomatic patients, sensitivity was 33%. All Immunoglobulin-A-positive patients resulted negative for RAT. The RAT might represent a useful resource in selected clinical settings as a complementary tool in RT-PCR for rapid patient triaging, but the lower sensitivity, especially in late presenters and COVID-19 asymptomatic subjects, must be taken into account.

scholarly journals Performance of Seven SARS-CoV-2 Self-Tests Based on Saliva, Anterior Nasal and Nasopharyngeal Swabs Corrected for Infectiousness in Real-Life Conditions: A Cross-Sectional Test Accuracy Study

Diagnostics ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1567
Author(s):  
Miroslav Homza ◽  
Hana Zelena ◽  
Jaroslav Janosek ◽  
Hana Tomaskova ◽  
Eduard Jezo ◽  
...  
Keyword(s):  
Real Life ◽  
High Capacity ◽  
Nasopharyngeal Swab ◽  
Test Accuracy ◽  
Cross Sectional ◽  
Predictive Values ◽  
Nasal Swabs ◽  
Accuracy Study ◽  
Testing Center ◽  
Antigen Tests

Many studies reported good performance of nasopharyngeal swab-based antigen tests for detecting SARS-CoV-2-positive individuals; however, studies independently evaluating the quality of antigen tests utilizing anterior nasal swabs or saliva swabs are still rare, although such tests are widely used for mass testing. In our study, sensitivities, specificities and predictive values of seven antigen tests for detection of SARS-CoV-2 (one using nasopharyngeal swabs, two using anterior nasal swabs and four using saliva) were evaluated. In a setting of a high-capacity testing center, nasopharyngeal swabs for quantitative PCR (qPCR) were taken and, at the same time, antigen testing was performed in accordance with manufacturers’ instructions for the respective tests. In samples where qPCR and antigen tests yielded different results, virus culture was performed to evaluate the presence of the viable virus. Sensitivities and specificities of individual tests were calculated using both qPCR and qPCR corrected for viability as the reference. In addition, calculations were also performed for data categorized according to the cycle threshold and symptomatic status. The test using nasopharyngeal swabs yielded the best results (sensitivity of 80.6% relative to PCR and 91.2% when corrected for viability) while none of the remaining tests (anterior nasal swab or saliva-based tests) came even close to the WHO criteria for overall sensitivity. Hence, we advise caution when using antigen tests with alternative sampling methods without independent validation.

scholarly journals Comparison of Saliva and Nasopharyngeal Swab Nucleic Acid Amplification Testing for Detection of SARS-CoV-2

2021 ◽  
Author(s):  
Guillaume Butler-Laporte ◽  
Alexander Lawandi ◽  
Ian Schiller ◽  
Mandy C. Yao ◽  
Nandini Dendukuri ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acid Amplification ◽  
Nasopharyngeal Swab ◽  
Nucleic Acid Amplification Testing

scholarly journals High performances of a novel antigen detection test on nasopharyngeal specimens for SARS-CoV-2 infection diagnosis: a prospective study

2020 ◽  
Author(s):  
Laura Courtellemont ◽  
jerome Guinard ◽  
Clemence Guillaume ◽  
Susanna Giache ◽  
Vincent Rzepecki ◽  
...  
Keyword(s):  
Prospective Study ◽  
Large Scale ◽  
Quantitative Polymerase Chain Reaction ◽  
Real Life ◽  
Rapid Test ◽  
Threshold Value ◽  
Public Health Issue ◽  
Nasopharyngeal Swab ◽  
Specificity And Sensitivity ◽  
Asymptomatic Patients

Introduction The SARS-CoV-2 pandemic has become a major public health issue worldwide. Developing and evaluating rapid and easy-to-perform diagnostic tests is an absolute priority. The current prospective study was designed to assess diagnostic performances of an antigen-based rapid detection test (COVID-VIRO) in a real-life setting. Methods Two nasopharyngeal specimens of symptomatic or asymptomatic adult patients hospitalized in the Infectious Diseases Department or voluntarily accessing the COVID-19 Screening Department of the Regional Hospital of Orleans, France, were concurrently collected. COVID VIRO diagnostic specificity and sensitivity were assessed in comparison to real-time reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) results. A subgroup of patients underwent an additional oropharyngeal and/or a saliva swab for rapid testing. Results 121 patients already having a confirmed infection and 127 patients having no evidence of recent or ongoing infection were enrolled, for a total of 248 couple of nasopharyngeal swab specimens. Overall COVID-VIRO sensitivity was 96.7% (IC: 93.5%-99.9%). In asymptomatic patients, patients having symptoms for more than 4 days and those having a RT-qPCR Cycle threshold value >32, sensitivity was of 100%, 95.8% and 96.9% respectively. The concordance between RT-qPCR and COVID VIRO rapid test was 100% for the 127 patients with no SARS-CoV-2 infection. Conclusion COVID-VIRO test had 100% specificity and above 95% sensitivity, better than WHO recommendations (specificity ≥97-100%, sensitivity ≥80%). These rapid tests are particularly interesting for large-scale screening in Emergency Department, low resource settings and airports.

scholarly journals Insights into the SARS-CoV-2 Diagnosis in India: Present Status and Future Prospects

2021 ◽  
pp. 38-53
Author(s):  
Laxmipreeya Behera ◽  
Jyoti Prakash Sahoo ◽  
Sushree Suparna Mahapatra ◽  
Jannila Praveena ◽  
Trupti Dash ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Rna Virus ◽  
Surface Protein ◽  
Nucleic Acid Amplification ◽  
Serological Tests ◽  
Test Loop ◽  
In Vitro Diagnostic ◽  
Lateral Flow Assays ◽  
Antigen Tests

COVID-19, the infectious pandemic disease is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This deadly disease was unknown before its catastrophic outbreak of the infection in Wuhan city of China, in December 2019. The pandemic situation has increased the demand of rapid enhancement of the in-vitro diagnostic assays which would enable the mass screening and testing. Several molecular and serological diagnostics assays such as direct viral antigen tests, nucleic acid amplification tests and serological tests were developed. Nucleic acid tests such as RT-PCR. TrueNAT, Feluda Test, loop-mediated isothermal amplification (LAMP) etc. detect the presence of RNA virus in the nasal or throat swab or from saliva. Antigen tests detect the presence of a virus as the antigen, which is a surface protein. Antibody tests such as enzyme-linked immunosorbent assays (ELISA), lateral flow assays (LFA), chemiluminescence assays (CLIA) etc. detect the presence of antibodies generated against SARS-CoV-2 in the blood samples.

scholarly journals IFCC interim guidelines on rapid point-of-care antigen testing for SARS-CoV-2 detection in asymptomatic and symptomatic individuals

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mary Kathryn Bohn ◽  
Giuseppe Lippi ◽  
Andrea R. Horvath ◽  
Rajiv Erasmus ◽  
Matthias Grimmler ◽  
...  
Keyword(s):  
Clinical Chemistry ◽  
Point Of Care ◽  
Nucleic Acid Amplification ◽  
Test Interpretation ◽  
Suitable Alternative ◽  
Target Populations ◽  
Evaluation Test ◽  
Conventional Instrumentation ◽  
Antigen Tests ◽  
Antigen Testing

Abstract With an almost unremittent progression of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections all around the world, there is a compelling need to introduce rapid, reliable, and high-throughput testing to allow appropriate clinical management and/or timely isolation of infected individuals. Although nucleic acid amplification testing (NAAT) remains the gold standard for detecting and theoretically quantifying SARS-CoV-2 mRNA in various specimen types, antigen assays may be considered a suitable alternative, under specific circumstances. Rapid antigen tests are meant to detect viral antigen proteins in biological specimens (e.g. nasal, nasopharyngeal, saliva), to indicate current SARS-CoV-2 infection. The available assay methodology includes rapid chromatographic immunoassays, used at the point-of-care, which carries some advantages and drawbacks compared to more conventional, instrumentation-based, laboratory immunoassays. Therefore, this document by the International Federation for Clinical Chemistry and Laboratory Medicine (IFCC) Taskforce on COVID-19 aims to summarize available data on the performance of currently available SARS-CoV-2 antigen rapid detection tests (Ag-RDTs), providing interim guidance on clinical indications and target populations, assay selection, and evaluation, test interpretation and limitations, as well as on pre-analytical considerations. This document is hence mainly aimed to assist laboratory and regulated health professionals in selecting, validating, and implementing regulatory approved Ag-RDTs.

scholarly journals Quantitative comparison of SARS-CoV-2 nucleic acid amplification test and antigen testing algorithms: a decision analysis simulation model

2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Phillip P. Salvatore ◽  
Melisa M. Shah ◽  
Laura Ford ◽  
Augustina Delaney ◽  
Christopher H. Hsu ◽  
...  
Keyword(s):  
Public Health ◽  
Nucleic Acid ◽  
Decision Analysis ◽  
Quantitative Comparison ◽  
Nucleic Acid Amplification ◽  
Health Organizations ◽  
Trade Offs ◽  
Public Health Organizations ◽  
Testing Algorithms ◽  
Antigen Tests

Abstract Background Antigen tests for SARS-CoV-2 offer advantages over nucleic acid amplification tests (NAATs, such as RT-PCR), including lower cost and rapid return of results, but show reduced sensitivity. Public health organizations recommend different strategies for utilizing NAATs and antigen tests. We sought to create a framework for the quantitative comparison of these recommended strategies based on their expected performance. Methods We utilized a decision analysis approach to simulate the expected outcomes of six testing algorithms analogous to strategies recommended by public health organizations. Each algorithm was simulated 50,000 times in a population of 100,000 persons seeking testing. Primary outcomes were number of missed cases, number of false-positive diagnoses, and total test volumes. Outcome medians and 95% uncertainty ranges (URs) were reported. Results Algorithms that use NAATs to confirm all negative antigen results minimized missed cases but required high NAAT capacity: 92,200 (95% UR: 91,200-93,200) tests (in addition to 100,000 antigen tests) at 10% prevalence. Selective use of NAATs to confirm antigen results when discordant with symptom status (e.g., symptomatic persons with negative antigen results) resulted in the most efficient use of NAATs, with 25 NAATs (95% UR: 13-57) needed to detect one additional case compared to exclusive use of antigen tests. Conclusions No single SARS-CoV-2 testing algorithm is likely to be optimal across settings with different levels of prevalence and for all programmatic priorities. This analysis provides a framework for selecting setting-specific strategies to achieve acceptable balances and trade-offs between programmatic priorities and resource constraints.

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