Due to their ease-of-use, lateral flow assay SARS-CoV-2 antigen-detecting rapid diagnostic tests could be suitable candidates for antigen-detecting rapid diagnostic self-test (Ag-RDST). We evaluated the practicability of the Ag-RDST BIOSYNEX Antigen Self-Test COVID-19 Ag+ (Biosynex Swiss SA, Freiburg, Switzerland), using self-collected nasal secretions from the turbinate medium (NMT), in 106 prospectively included adult volunteers living in Paris, France. The majority of the participants correctly understood the instructions for use (94.4%; 95% confidence interval (CI): 88.3–97.4), showing a great ability to perform the entire self-test procedure to obtain a valid and interpretable result (100%; 95% CI: 96.5–100), and demonstrated the ability to correctly interpret test results (96.2%; 95% CI: 94.2–97.5) with a high level of general satisfaction. About one in eight participants (# 15%) needed verbal help to perform or interpret the test, and only 3.8% of test results were misinterpreted. By reference to multiplex real-time RT-PCR, the Ag-RDST showed 90.9% and 100% sensitivity and specificity, respectively, and high agreement (98.1%), reliability (0.94), and accuracy (90.9%) to detect SARS-CoV-2 antigen. Taken together, our study demonstrates the high usability and accuracy of BIOSYNEX Antigen Self-Test COVID-19 Ag+ for supervised self-collected NMT sampling in an unselected adult population living in France.

Background The accuracy and reliability of rapid diagnostic tests are critical for monitoring and diagnosing SARS-CoV-2 infection in the general population. This study aimed to evaluate the analytical performance of the BIOSYNEX COVID-19 Ag BSS (Biosynex Swiss SA, Fribourg, Switzerland) antigen rapid diagnostic test (BIOSYNEX Ag-RDT), which targets the SARS-CoV-2 N-nucleocapsid protein for the diagnosis of COVID-19. The Ag-RDT was compared with a real-time RT-PCR (rtRT-PCR) as gold standard for performance measurement. Methods Two nasopharyngeal flocked swabs were prospectively collected simultaneously in March and April 2021 from 967 individuals aged ≥ 18 years tested for SARS-CoV-2 in two private laboratories, Paris, France. Results Overall, the Ag-RDT demonstrated high sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 81.8%, 99.6%, 96.6%, and 97.5%, respectively. The agreement (97.0%), reliability assessed using Cohen’s κ-coefficient (0.87), and accuracy evaluated using Youden index (J) (81.6%) in detecting SARS-CoV-2 were high. The analytical performance of the Ag-RDT remained high when there was significant viral shedding (i.e., N gene Ct values ≤ 33 on reference RT-PCR). The sensitivity was only 55.2% in case of low or very low viral excretion (Ct > 33). Conclusions The BIOSYNEX Ag-RDT is a promising, potentially simple diagnostic tool, especially in symptomatic COVID-19 patients with substantial viral excretion in the nasopharynx.

Background: The accuracy and reliability of rapid diagnostic tests are critical for monitoring and diagnosing SARS-CoV-2 infection in the general population. This study aimed to evaluate the analytical performance of the BIOSYNEX COVID-19 Ag BSS (Biosynex Swiss SA, Fribourg, Switzerland) antigen rapid diagnostic test (Ag-RDT), which targets the SARS-CoV-2 N-nucleocapsid protein for the diagnosis of COVID-19. The Ag-RDT was compared with a real-time RT-PCR (rtRT-PCR) gold standard for performance measurement.Methods: Two nasopharyngeal flocked swabs were prospectively collected simultaneously in March and April 2021 from 967 individuals aged ≥18 years tested for SARS-CoV-2 in two private laboratories, Paris, France.Results: Overall, the Ag-RDT demonstrated high sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 81.8%, 99.6%, 96.6%, and 97.5%, respectively, as well as high or near-perfect agreement (97.0%), reliability was assessed using Cohen’s κ-coefficient (0.87), and accuracy was evaluated using Youden index (J) (81.6%) in detecting SARS-CoV-2. The analytical performance of the Ag-RDT remained high when there was significant viral shedding (i.e., N gene Ct values ≤ 33 on reference RT-PCR). The sensitivity was only 55.2% in case of low or very low viral excretion (Ct> 33).Conclusions: The BIOSYNEX COVID-19 Ag BSS Ag-RDT is a promising, potentially simple diagnostic tool, especially in symptomatic COVID -19 or proven infectiousness.

Background: Evaluating the accuracy and reliability of rapid diagnostic testing kits is crucial for surveillance and diagnosis of SARS-CoV-2 infections in general population. The aim of the study was to assess the analytical performances of the antigen-rapid diagnosis test (Ag-RDT) BIOSYNEX COVID-19 Ag BSS (Biosynex Swiss SA, Freiburg, Switzerland), targeting the SARS-CoV-2 N nucleocapsid protein, for the diagnosis of COVID-19, by reference to real-time RT-PCR (rtRT-PCR).Methods: A total 967 adults living in Paris region were prospectively included during the third wave of the COVID-19 epidemic in France. Paired nasopharyngeal flocked swabs were collected at the same timepoint from persons aged ≥18 years receiving testing for SARS-CoV-2, at two private laboratories.Results: Overall, the Ag-RDT showed high sensitivity, specificity, PPV and NPV of 81.8%, 99.6%, 96.6% and 97.5%, respectively, as well as high or almost perfect agreement (97.0%), reliability assessed by Cohen’s κ coefficient (0.87), and accuracy assessed by Youden’s J index (81.6%) to detect SARS-CoV-2. The analytical performances of the Ag-RDT remained high in the event of significant viral excretion (i.e., N gene Ct values ≤ 33 by reference rtRT-PCR), while the sensitivity of the Ag-RDT dropped to 55.2% with low or very low viral shedding (Ct> 33).Conclusions: The Ag-RDT BIOSYNEX COVID-19 Ag BSS showed high specificity and sufficient sensitivity for the detection of SARS-CoV-2. This test is a promising potential easy diagnostic tool, especially in situations of symptomatic COVID-19 and/or proven contagiousness.