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Since the emergence of a novel infection due to the SARS-CoV-2 virus (COVID-19), the World Health Organization has urged countries to develop diagnostic tests to combat the pandemic. Molecular assays were developed following the release of the gene sequence of the virus in January 2020. Reverse transcription-quantitative PCR (RT-qPCR) is taken as the gold standard for the diagnosis of COVID-19. However, due to its limitations, highly sensitive methods for detecting antigens (antigen rapid diagnostic tests) have been developed that would help in a timely and accurate diagnosis. Antigen rapid diagnostic tests (Ag-RDTs) can help guide patient management at the point of care by random screening, re-testing, and timely decision-making in the field of public health. When the affordability and validity of the diagnostic assay are involved, no assay can show 100% correct results. Further studies need to be done to better understand the response of the Ag-RDTs in different settings. Nevertheless, Ag-RDTs can play a complementary role in the response and case management of COVID-19.
Coronavirus disease 2019, COVID-19, emerged from the Wuhan province of China at the end of 2019 [
Most of the tests that were developed to detect SARS-CoV-2 relied on viral RNA amplification. The tests typically use polymerase chain reaction (PCR) to detect viral RNA. These molecular tests are highly sensitive and specific. Reverse transcription-quantitative PCR (RT-qPCR) through nasopharyngeal swabs, throat swabs, or saliva is considered the gold standard for the diagnosis of COVID-19 [
Ag-RDTs diagnose SARS-CoV-2 active infection by the detection of viral proteins in different types of specimens. These are lateral flow, single-use, rapid tests that are processed or visually read using a small compact device [
Table
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Abbott BinaxNOW, USA | 97%/99% | Nasal swab | Yes | Yes |
Abbott Panbio, USA | 93%/99% | Nasal swab, nasopharyngeal swab | - | Yes |
Access Bio CareStart, USA | 88%/100% | Nasal swab, nasopharyngeal swab | Yes | - |
BD Veritor, USA | 84%/100% | Nasal swab | Yes | - |
LumiraDx, UK | 98%/97% | Nasal swab | Yes | - |
Quidel Sofia Flu and SARS Antigen Fluorescent Immunoassay, USA | 95%/100% | Nasal swab, nasopharyngeal swab | Yes | - |
SD Biosensor, South Korea | 97%/100% | Nasal swab, nasopharyngeal swab | - | Yes |
Ellume COVID-19 Home Test, |
95%/97% | Nasal swab | Yes | - |
Clip COVID Rapid Antigen Test, luminostics, Inc. USA | 97%/100% | Nasal swab | Yes | - |
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Quidel Corporation | QuickVue At-Home COVID-19 Test | 3/1/2021 | Lateral Flow, Visual Read, Prescription Home Testing |
Princeton BioMeditech Corp. | Status COVID-19/Flu | 2/4/2021 | Lateral Flow, Visual Read, Multi-analyte |
Quidel Corporation | QuickVue SARS Antigen Test | 12/18/2020 | Lateral Flow, Visual Read |
Abbott Diagnostics Scarborough, Inc. | BinaxNOW COVID-19 Ag Card Home Test | 12/16/2020 | Lateral Flow, Visual Read, Prescription Home Testing |
Ellume Limited | Ellume COVID-19 Home Test | 12/15/2020 | Lateral Flow, Fluorescence, Instrument Read, Over the Counter (OTC) Home Testing, Screening |
Luminostics, Inc. | Clip COVID Rapid Antigen Test | 12/7/2020 | Lateral flow immunoluminescent assay, instrument read |
Access Bio, Inc. | CareStart COVID-19 Antigen test | 10/8/2020 | Lateral Flow, Visual Read |
Quidel Corporation | Sofia 2 Flu + SARS Antigen FIA | 10/2/2020 | Lateral Flow, Fluorescence, Instrument Read, Multi-Analyte |
Abbott Diagnostics Scarborough, Inc. | BinaxNOW COVID-19 Ag Card | 8/26/2020 | Lateral Flow, Visual Read |
LumiraDx UK Ltd. | LumiraDx SARS-CoV-2 Ag Test | 8/18/2020 | Microfluidic Immunofluorescence Assay, Instrument Read |
Becton, Dickinson and Company (BD) | BD Veritor System for the Rapid Detection of SARS-CoV-2 | 7/2/2020 | Chromatographic Digital Immunoassay, Instrument Read |
Even though the Ag-RDTs approved by WHO or US FDA for emergency use show a consistent performance constant, the independent Ag-RDTs evaluation carried out by the foundation for innovative new diagnostics (FIND) showed that their performance differs in different countries based on the assessment panel and the viral load in the study samples [
Several Ag-RDT studies have been conducted globally. Lambert-Niclot
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Peto |
Deepblue, orient Gene, Abbott and Innova SARS-CoV-2 Antigen Rapid Qualitative Test | Viral antigen sensitivity was 78.8% (156/198, 95% CI: 72.4 - 84.3) | Lateral Flow Devices results are promising for large-scale population testing and identifying infectious positive individuals. |
Yin |
Panbio™ COVID-19 Ag Rapid Test Device, BD Veritor™ SARS-CoV-2, COVID-19 Ag Respi-Strip and SARS-CoV-2 Rapid Antigen Test (SD Biosensor) | All the rapid tests showed a sensitivity of 83.3% (95% CI: 78.2-87.4%). | Rapid tests can be used to cover a large target population by considering into account the ease to use, readiness of reagents and the rapid result, and molecular assays can be used for severely ill patients. |
Matsuda |
COVID-19 Ag ECO Test and Panbio COVID-19 Ag Rapid Test Abbott | Both the rapid tests' overall sensitivity was 87%, and specificity was 96%. | The rapid tests have an important role in improving testing strategies, notably in resource-constrained regions. |
Francis VR and Muthugala MARV (2021) [ |
STANDARD Q COVID-19 Ag test, SD Biosensor, | The overall sensitivity of the kit was 58.5% (95% CI: 44, 72) and specificity was 100%. | The rapid antigen test can be used as a primary screening test for community surveillance. |
A study in Spain reported the overall sensitivity of 48.1% with the PanbioTM COVID-19 Ag-RDT for the identification of SARS-CoV-2-infected individuals among asymptomatic close contacts of confirmed COVID-19 cases [
To ensure proper patient management and public health action, countries need to maintain a balance between benefits and risk outcomes of rapid Ag-RDT. When the affordability and validity of the diagnostic assay are involved, no assay can show 100% correct results. More research is needed to better understand the validity of rapid Ag-RDTs in various settings and to know how often and when to use these tests. This would support testing strategies and health policies and would disrupt the transmission of disease. However, antigen rapid diagnostic tests can play a supporting role in the management of the COVID-19 pandemic.
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The authors declare no conflict of interest, financial or otherwise.
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