Analytical performance of the point-of-care BIOSYNEX COVID-19 Ag BSS for the detection of SARS‐CoV‐2 nucleocapsid protein in nasopharyngeal swabs: a prospective field evaluation during the COVID-19 third wave in France

Abstract

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.

Update of European Society of Clinical Microbiology and Infectious Diseases coronavirus disease 2019 guidelines: diagnostic testing for severe acute respiratory syndrome coronavirus 2

“… In patients with signs and symptoms compatible with COVID-19, we suggest the use of laboratory based NAAT in nasopharyngeal samples versus rapid antigen detection testing in nasopharyngeal samples for the diagnosis of COVID-19. Weak against Very low [ 4 , 5 , 16 , 106 , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , 6 , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , 8 , [36] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] , 10 , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , 11 , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] ...…”

“… In patients ≥ 12 years old with signs and symptoms compatible with COVID-19, we suggest the use of laboratory-based NAAT versus rapid antigen detection testing for the diagnosis of COVID-19. Weak against Low [ 4 , 6 , 25 , 28 , 33 , 34 , 37 , [41] , [42] , [43] , [44] , 46 , 7 , 48 , 49 , [53] , [54] , [55] , [62] , [63] , [64] , 70 , 71 , 10 , 77 , 82 , 83 , 90 , 94 , 108 , 109 , 111 , 113 , 115 , 11 , 116 , 119 , 123 , 128 , 130 , 133 , [135] , [136] , [137] , 140 , 17 , [143] , [144] , [145] , [146] , [147] , [148] , [149] , [150] , [151] , ...…”

“… In asymptomatic patients ≥12 years old without risk factors for severe COVID-19, we suggest the use of laboratory-based NAAT versus rapid antigen testing for the diagnosis of COVID-19. Weak against Low [ 11 , 20 , 49 , 54 , 55 , 65 , 70 , 71 , 77 , 83 , 89 , 94 , 22 , 111 , 113 , 121 , 128 , 130 , 137 , [143] , [144] , [145] , [146] , 24 , [147] , [148] , [149] , 158 , [160] , [161] , [162] , [163] , [164] , [165] , 28 , [166] , [167] , [168] , [169] , [170] , [171] , [172] , [173] , [174] , [175] , 34 , 176 , 40 , 43 , 44 , 46 ] 3 In asymptomatic people of any age with any risk factor(s) for severe COVID-19 (including age <3 or ≥65 years) should rapid antigen tests be used, as compared to laboratory-based ...…”

Can Patients with Asymptomatic/Mild Illness and Moderate Illness COVID-19 Have White Matter Damage?

“…Coronavirus pandemic 2019 (COVID-19) quickly became a worldwide public health crisis and continues to spread worldwide. 1 , 2 In recent times, the study of long COVID, especially brain complications, has been intensely investigated. 3 , 4 Some studies have shown that severe COVID-19 infection could lead to white matter hyperintensities (WMHs).…”