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

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.

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Correlation of COVID-19 antigen test and CBNAAT results at a single tertiary care hospital in North India: an experience

International Journal of Community Medicine and Public Health ◽

10.18203/2394-6040.ijcmph20211768 ◽

2021 ◽

Vol 8 (5) ◽

pp. 2427

Author(s):

Surbhi Gupta ◽

Anju Shukla ◽

Poonam Singh ◽

Areena H. Siddiqui

Keyword(s):

Tertiary Care Hospital ◽

Point Of Care ◽

Tertiary Care ◽

Uttar Pradesh ◽

Nucleic Acid Amplification ◽

North India ◽

Care Hospital ◽

Antigen Test ◽

Discordant Group ◽

Antigen Tests

Background: Nucleic acid amplification test (NAAT) is considered gold standard in the molecular diagnosis of CoV-2 infection but since it is costly, labor intensive and needs technical expertise, rapid chromatographic immunoassay for the qualitative detection of specific antigens to SARS CoV-2 have been devised. Objectives of this study was to compare the results of Antigen test and NAAT for CoV-2 infection carried out during the months of July and August 2020 by single tertiary care hospital in Lucknow, Uttar Pradesh and to determine the utility of rapid antigen test in the SARS CoV-2 diagnosis.Methods: All the patients who came to our hospital seeking admission during July 2020 and August 2020 were included in the study. A total of 1000 patients were included in this study.Results: Out of a total 1000 cases which were included in the study, 769 cases (76.9%) were found to be SARS CoV-2 negative by both antigen and CBNAAT, 100 cases (10.0%) were SARS CoV-2 positive by both antigen and CBNAAT tests. But in 131 cases (13.1%), antigen was not able to pick up the disease. It was also found that the Cycle Threshold (Ct) value for the discordant group was higher (Mean E= 28, Mean N2=33) when compared to the group where antigen was positive.Conclusions: The present study establishes the role of rapid antigen tests in contributing to the quick, point of care diagnosis of SARS CoV-2. These assays are safe, simple, and fast and can be used in local clinics and hospitals. These tests are very important for real-time patient management and infection control decision.

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The Performance of Two Rapid Antigen Tests During Population-Level Screening for SARS-CoV-2 Infection

Frontiers in Medicine ◽

10.3389/fmed.2021.797109 ◽

2021 ◽

Vol 8 ◽

Author(s):

Mohammad Alghounaim ◽

Hamad Bastaki ◽

Farah Bin Essa ◽

Hoda Motlagh ◽

Salman Al-Sabah

Keyword(s):

Positive Predictive Value ◽

Prospective Study ◽

Predictive Value ◽

Point Of Care ◽

Population Level ◽

Lower Sensitivity ◽

Rt Pcr ◽

Antigen Tests ◽

A Prospective Study ◽

Antigen Testing

Background: SARS-CoV-2 antigen assays offer a rapid mean to diagnose and isolate infected individuals. However, their utility in population-level screening is unknown.Objectives: The performance of two antigen tests in detecting SARS-CoV-2 was assessed among individuals randomly selected in the community.Study Design: A prospective study that performed head-to-head comparison of two SARS-CoV-2 antigen assays. Individuals were recruited during community SARS-CoV-2 screening over 10 working days. Demographic and clinical data were collected. Standard Q COVID-19 Ag test, a point-of-care chromatographic assay, was conducted immediately, and then the sample was transported to the virology laboratory to perform PCR and the LIAISON SARS-CoV-2 Ag chemiluminesence immunoassay.Results: respiratory samples from 991 individuals were collected, and 62 were positive by PCR. Inconclusive PCR results were observed in 19 samples and were excluded. The median age of participants was 40.2 years (IQR 32.3–47.8), and 932 (94%) were males. Most (77.4%) of infections were asymptomatic. The sensitivity and the specificity of the LIAISON assay were 43.3% (95%CI 30.6–56.8) and 99.9% (95%CI 99.3–100). The Standard Q assay had lower sensitivity (30.6%, 95%CI 19.6–43.7) but similar specificity (98.8%, 95%CI, 97.8–99.4). Similarly, the LIAISON assay had higher positive predictive value (96.3%, 95%CI 81–99.9% vs. 63.3%, 95%CI, 43.9–80.1%). Both assays performed better in symptomatic patients and among samples with a low-cycle threshold (Ct < 25).Conclusion: In our setting of random community surveillance, rapid antigen testing of nasopharyngeal swabs by either LIAISON SARS-CoV-2 Ag (DiaSorin) or Standard Q COVID-19 Ag (SD Biosensor) was less sensitive to detecting SARS-CoV-2 than the TaqPath COVID-19 RT-PCR.

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

10.1101/2021.03.15.21253608 ◽

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.

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Logistic advantage of two-step screening strategy for SARS-CoV-2 at airport quarantine

10.1101/2021.01.25.21250509 ◽

2021 ◽

Author(s):

Isao Yokota ◽

Peter Y Shane ◽

Takanori Teshima

Keyword(s):

Point Of Care ◽

High Accuracy ◽

Screening Strategy ◽

Nucleic Acid Amplification ◽

Point Of Care Testing ◽

Chain Reaction ◽

False Negatives ◽

Imported Cases ◽

Polymerase Chain ◽

Antigen Testing

SummaryBackgroundAirport quarantine is required to reduce the risk of entry of travelers infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, it is challenging for both high accuracy and rapid turn-around time to coexist in testing; polymerase chain reaction (PCR) is time-consuming with high accuracy, while antigen testing is rapid with less accuracy.Methods88,924 (93.2%) of 95,457 arrivals at three international airports in Japan were tested for SARS-CoV-2 using self-collected saliva by a screening strategy with initial chemiluminescent enzyme immunoassay (CLEIA) followed by confirmatory nucleic acid amplification tests (NAAT) only for intermediate range antigen concentrations.Results254 (0.27%) persons were found to be SARS-CoV-2 antigen positive (≥ 4.0 pg/mL) by CLEIA. NAAT was required for confirmatory testing in 513 (0.54%) persons with intermediate antigen concentrations (0.67-4.0 pg/mL) whereby the virus was detected in 34 (6.6%) persons. This two-step strategy dramatically reduced the utilization of NAAT to approximately one out of every 200 test subjects.Estimated performance of this strategy did not show significant increase in false negatives as compared to performing NAAT in all subjects. Further reduction in imported cases may be achieved by post-screening quarantine.ConclusionsPoint of care testing by quantitative CLEIA using self-collected saliva is less labor-intensive and yields results rapidly, thus suitable as an initial screening test. Reserving NAAT for CLEIA indeterminate cases may prevent compromising accuracy while significantly improving the logistics of administering mass-screening at large venues.

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IFCC interim guidelines on serological testing of antibodies against SARS-CoV-2

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2020-1413 ◽

2020 ◽

Vol 0 (0) ◽

Cited By ~ 3

Author(s):

Mary Kathryn Bohn ◽

Tze Ping Loh ◽

Cheng-Bin Wang ◽

Robert Mueller ◽

David Koch ◽

...

Keyword(s):

Clinical Utility ◽

Clinical Chemistry ◽

Mitigation Strategies ◽

Molecular Testing ◽

Test Interpretation ◽

Serological Testing ◽

Target Populations ◽

Performance Requirements ◽

Clinical Laboratories ◽

Pandemic Response

AbstractSerological testing for the detection of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is emerging as an important component of the clinical management of patients with coronavirus disease 2019 (COVID-19) as well as the epidemiological assessment of SARS-CoV-2 exposure worldwide. In addition to molecular testing for the detection of SARS-CoV-2 infection, clinical laboratories have also needed to increase testing capacity to include serological evaluation of patients with suspected or known COVID-19. While regulatory approved serological immunoassays are now widely available from diagnostic manufacturers globally, there is significant debate regarding the clinical utility of these tests, as well as their clinical and analytical performance requirements prior to application. This document by the International Federation for Clinical Chemistry and Laboratory Medicine (IFCC) Taskforce on COVID-19 provides interim guidance on: (A) clinical indications and target populations, (B) assay selection, (C) assay evaluation, and (D) test interpretation and limitations for serological testing of antibodies against SARS-CoV-2 infection. These evidence-based recommendations will provide practical guidance to clinical laboratories in the selection, verification, and implementation of serological assays and are of the utmost importance as we expand our pandemic response from initial case tracing and containment to mitigation strategies to minimize resurgence and further morbidity and mortality.

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Performance characteristics of the Abbott BinaxNOW SARS-CoV-2 antigen test in comparison to real-time RT-PCR and viral culture in community testing sites during November 2020

Journal of Clinical Microbiology ◽

10.1128/jcm.01742-21 ◽

2021 ◽

Author(s):

Olivia Almendares ◽

Jessica L. Prince-Guerra ◽

Leisha D. Nolen ◽

Jayleen K.L. Gunn ◽

Ariella P. Dale ◽

...

Keyword(s):

Real Time ◽

Point Of Care ◽

Exposure Period ◽

Rapid Identification ◽

Nucleic Acid Amplification ◽

Test Results ◽

Antigen Test ◽

Viral Culture ◽

Pima County ◽

Antigen Tests

Point-of-care antigen tests are an important tool for SARS-CoV-2 detection. Antigen tests are less sensitive than real-time reverse-transcriptase PCR (rRT-PCR). Data on the performance of the BinaxNOW antigen test compared to rRT-PCR and viral culture by symptom and known exposure status, timing during disease or exposure period and demographic variables are limited. During November 3 rd -17 th , 2020, we collected paired upper respiratory swab specimens to test for SARS-CoV-2 by rRT-PCR and Abbott BinaxNOW (BinaxNOW) antigen test at two community testing sites in Pima County, Arizona. We administered a questionnaire to capture symptoms, known exposure status and previous SARS-CoV-2 test results. Specimens positive by either test were analyzed by viral culture. Previously we showed overall BinaxNOW sensitivity was 52.5%. Here we showed BinaxNOW sensitivity increased to 65.7% among currently symptomatic individuals reporting a known exposure. BinaxNOW sensitivity was lower among participants with a known exposure and previously symptomatic (32.4%) or never symptomatic (47.1%) within 14 days of testing. Sensitivity was 71.1% in participants within a week of symptom onset. In participants with a known exposure, sensitivity was highest 8-10 days post-exposure (75%). The positive predictive value for recovery of virus in cell culture was 56.7% for BinaxNOW-positive and 35.4% for rRT-PCR-positive specimens. Result reporting time was 2.5 hours for BinaxNOW and 26 hours for rRT-PCR. Point-of-care antigen tests have a shorter turn-around time compared to laboratory-based nucleic acid amplification tests, which allows for more rapid identification of infected individuals. Antigen test sensitivity limitations are important to consider when developing a testing program.

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

BMC Infectious Diseases ◽

10.1186/s12879-021-06524-7 ◽

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.

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Development and Efficacy of Lateral Flow Point-of-Care Testing Devices for Rapid and Mass COVID-19 Diagnosis by the Detections of SARS-CoV-2 Antigen and Anti-SARS-CoV-2 Antibodies

Diagnostics ◽

10.3390/diagnostics11101760 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1760

Author(s):

Wen-Yeh Hsieh ◽

Cheng-Han Lin ◽

Tzu-Ching Lin ◽

Chao-Hsu Lin ◽

Hui-Fang Chang ◽

...

Keyword(s):

Large Scale ◽

Point Of Care ◽

Standard Procedure ◽

Surface Enhanced Raman Spectroscopy ◽

Lateral Flow ◽

Control Measures ◽

Nucleic Acid Amplification ◽

Antibody Detection ◽

Infection Prevention And Control ◽

Antigen Tests

The COVID-19 pandemic is an ongoing global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2020–2021. COVID-19 is becoming one of the most fatal pandemics in history and brings a huge challenge to the global healthcare system. Opportune detection, confinement, and early treatment of infected cases present the first step in combating COVID-19. Diagnosis via viral nucleic acid amplification tests (NAATs) is frequently employed and considered the standard procedure. However, with an increasing urge for point-of-care tests, rapid and cheaper immunoassays are widely utilized, such as lateral flow immunoassay (LFIA), which can be used for rapid, early, and large-scale detection of SARS-CoV-2 infection. In this narrative review, the principle and technique of LFIA applied in COVID-19 antigen and antibody detection are introduced. The diagnostic sensitivity and specificity of the commercial LFIA tests are outlined and compared. Generally, LFIA antigen tests for SARS-CoV-2 are less sensitive than viral NAATs, the “gold standard” for clinical COVID-19 diagnosis. However, antigen tests can be used for rapid and mass testing in high-risk congregate housing to quickly identify people with COVID-19, implementing infection prevention and control measures, thus preventing transmission. LFIA anti-SARS-CoV-2 antibody tests, IgM and/or IgG, known as serology tests, are used for identification if a person has previously been exposed to the virus or vaccine immunization. Notably, advanced techniques, such as LFT-based CRISPR-Cas9 and surface-enhanced Raman spectroscopy (SERS), have added new dimensions to the COVID-19 diagnosis and are also discussed in this review.

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

Diagnosis ◽

10.1515/dx-2020-0131 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Camilla Mattiuzzi ◽

Brandon M. Henry ◽

Giuseppe Lippi

Keyword(s):

Severe Acute Respiratory Syndrome ◽

Point Of Care ◽

Turnaround Time ◽

Molecular Testing ◽

Upper Respiratory Tract ◽

Making Sense ◽

Skilled Personnel ◽

Potential Benefits ◽

Antigen Testing ◽

Care Availability

AbstractAlthough 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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Screening, Diagnostic and Prognostic Tests for COVID-19: A Comprehensive Review

Life ◽

10.3390/life11060561 ◽

2021 ◽

Vol 11 (6) ◽

pp. 561

Author(s):

Mariana Ulinici ◽

Serghei Covantev ◽

James Wingfield-Digby ◽

Apostolos Beloukas ◽

Alexander G. Mathioudakis ◽

...

Keyword(s):

Point Of Care ◽

Standard Test ◽

Current Evidence ◽

Molecular Testing ◽

Rt Pcr ◽

Diagnostic Screening ◽

Comprehensive Review ◽

Prognostic Tests ◽

Polymerase Chain ◽

Antigen Testing

While molecular testing with real-time polymerase chain reaction (RT-PCR) remains the gold-standard test for COVID-19 diagnosis and screening, more rapid or affordable molecular and antigen testing options have been developed. More affordable, point-of-care antigen testing, despite being less sensitive compared to molecular assays, might be preferable for wider screening initiatives. Simple laboratory, imaging and clinical parameters could facilitate prognostication and triage. This comprehensive review summarises current evidence on the diagnostic, screening and prognostic tests for COVID-19.

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