Lateral Flow Immunoassays for SARS-CoV-2

Abstract

The continued circulation of SARS-CoV-2 virus in different parts of the world opens up the possibility for more virulent variants to evolve even as the coronavirus disease 2019 transitions from pandemic to endemic. Highly transmissible and virulent variants may seed new disruptive epidemic waves that can easily put the healthcare system under tremendous pressure. Despite various nucleic acid-based diagnostic tests that are now commercially available, the wide applications of these tests are largely hampered by specialized equipment requirements that may not be readily available, accessible and affordable in less developed countries or in low resource settings. Hence, the availability of lateral flow immunoassays (LFIs), which can serve as a diagnostic tool by detecting SARS-CoV-2 antigen or as a serological tool by measuring host immune response, is highly appealing. LFI is rapid, low cost, equipment-free, scalable for mass production and ideal for point-of-care settings. In this review, we first summarize the principle and assay format of these LFIs with emphasis on those that were granted emergency use authorization by the US Food and Drug Administration followed by discussion on the specimen type, marker selection and assay performance. We conclude with an overview of challenges and future perspective of LFI applications.

Keywords: antibody; antigen; diagnostic; dipstick; immunochromatography; immunosensor; point-of-care; serology.

Figure 1

(a) Assembly of the different components of LFI. Assay formats for the detection of SARS-CoV-2 antigen (b), IgM and IgG (c,d), and total antibody (e). TL, test line; CL, control line; Ab, antibody.

Figure 2

Sensitivity and specificity of commercial LFIs for the detection of SARS-CoV-2 antigen. (1). BD Veritor System for Rapid Detection of SARS-CoV-2 (VRD) (Becton, Dickinson and Company, Bergen, NJ, USA); (2). BinaxNOW COVID-19 Ag Card (Abbott Diagnostics, Chichago, IL, USA), (3). Biocredit COVID-19 Ag Detection Kit (RapiGEN, Anyang, South Korea); (4). Bioeasy 2019-Novel Coronavirus (2019-nCoV) Fluorescence Antigen Rapid Test Kit (fluorescence immunochromatographic assay) (Bioeasy Biotechnology, Shenzhen, China); (5). COVID-19 Ag Respi-Strip (Coris Bioconcept, Gembloux, Belgium); (6). COVID-VIRO (AAZ, Boulogne Billancourt, France); (7). Diagnostic Kit for 2019-nCoV Ag Test (Bioeasy Biotechnology, Shenzhen, China); (8). Huaketai New Coronavirus (Savant Biotechnology, Beijing, China); (9). Innova Lateral Flow Device (Innova Medical Group, Pasadena, CA, USA); (10). NADAL COVID-19 Ag Test (Nal Von Minden GmbH, Moers, Germany); (11). Panbio COVID-19 Ag Rapid Test Device (Abbott Rapid Diagnostics, Cologne, Germany); (12). Rapid antigen test provided by R-Biopharm; (13). Rapid COVID-19 Antigen Test (Healgen, Houston, TX, USA); (14). RIDA QUICK SARS-CoV-2 Antigen (R-Biopharm, Darmstadt, Germany); (15). SD Biosensor SARS-CoV-2 Rapid Antigen Test (Roche Diagnostics, Basel, Switzerland); (16). STANDARD Q COVID-19 Ag (SD Biosensor, Suwon-si, Republic of Korea); (17). StrongStep COVID-19 Antigen Test (Liming Bio-Products, Nanjing, China). * FDA-EUA.