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

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.

Evaluation of the performance of an immunoturbidimetric HbA1c reagent applied to the Siemens ADVIA 2400 automatic analyzer.

OBJECTIVES: A new immunochemical reagent based on latex particles and antibodies against HbA1c (Axis-Shield), using Siemens ADVIA 2400 Instrument was evaluated. DESIGN AND METHODS: Intra-assay and total imprecision, interferences studies (bilirubin ~850 µmol/L, triglycerides ~16.9 mmol/L, total protein ~140 g/L, sodium cyanate ~50 mg/dL, ascorbic acid ~50 mg/dL, urea ~24.99 mmol/L, glucose ~105.46 mmol/L, rheumatoid factor ~600 U/mL), method comparison vs Capillary Electrophoresis (Sebia), Lot to Lot reproducibility, linearity and carry over were conducted on ADVIA 2400 according to CLSI protocols. Additionally, 40 samples were measured by the two methods and also by a NGSP reference lab. RESULTS: CVs % obtained by intra-assay imprecision, on 3 human HbA1c specimens at different concentrations (48, 48-64 and >64 mmol/mol) in 20 replicates, were <4%. CVs % by total imprecision, performed over 20 days with 4 calibrations on 3 human HbA1c samples (48, 48-64 and >64 mmol/mol), resulted <4%. Interferences were studied on two human samples (42-53 and>64 mmol/mol) without obtaining significant biases (<10%). Methods comparison vs Capillary Electrophoresis, performed on 120 samples ranging 23-137 mmol/mol, obtaining r = 0.974 as regression coefficient and a mean bias at decision level (48 mmol/mol) <3%. The results obtained with the NGSP samples have allowed the certification of the new reagent. CONCLUSIONS: The ASD reagent met the needs of clinical laboratories, fulfilling both NGSP and IFCC requirements and it is robust to endogenous interferences.