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.

Efficacy of Fluorecare SARS-CoV-2 Spike Protein Test Kit for SARS-CoV-2 detection in nasopharyngeal samples of 121 individuals working in a manufacturing company

“…Recent guidelines published by the World Health Organization (WHO) and the Task Force on COVID-19 of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) [ 10 , 11 ] have suggested the potential use of antigen rapid tests in biological materials, in particular NP samples and saliva, for mass testing. Antigen-based assays use monoclonal anti-SARS-CoV-2 antibodies, which recognize SARS-CoV-2 antigens, mainly N and S (Nucleocapsid protein and Spike surface glycoprotein, respectively) [ 12 ].…”

“…≥0.97) and acceptable sensitivity (i.e. ≥0.80) [ 10 , 11 ]. Indeed, it is pivotal that such tests give reliable and reproducible results.…”

FebriDx for rapid screening of patients with suspected COVID-19 upon hospital admission: systematic literature review and meta-analysis

“…The diagnostic accuracy of Ag-RDTs has been thoughtfully reviewed by many recent meta-analyses, which revealed that their sensitivity compared to reference molecular techniques is considerably low, typically in the range of 0.59-0.76 [ 6 ], 0.66-0.88 [ 7 ], or 0.57-0.71 [ 8 ] depending on the different populations and according to the distinct strategy used for pooling data. Therefore, although they can be rapidity performed outside of conventional clinical laboratories, the low accuracy does not enable efficient triage of COVID-19, leaving under-diagnosed up to one-third of subjects with SARS-CoV-2 infection [ 9 ].…”

Rapid antigen testing for SARS-CoV-2 infection in a university setting in Ireland: Learning from a 6-week pilot study

“…In these settings, a Ag-RDT positive should be considered preliminary, with individuals isolating until a PCR test result is known. Ag-RDT negative individuals should continue to comply with conventional risk mitigation measures [ 10 ]. Ag-RDTs will be most effective when used regularly, with high levels of participation.…”