On-field evaluation of a ultra-rapid fluorescence immunoassay as a frontline test for SARS-CoV-2 diagnostic

• Published in: Journal of virological methods 2021-09, Vol.295, p.114201-114201, Article 114201
• Main Authors: Orsi, Andrea, Pennati, Beatrice Marina, Bruzzone, Bianca, Ricucci, Valentina, Ferone, Diego, Barbera, Paolo, Arboscello, Eleonora, Dentone, Chiara, Icardi, Giancarlo
• Format: Article
• Language: English
• Subjects: Antigens, Viral - analysis; Coronavirus Nucleocapsid Proteins - analysis; COVID-19 - diagnosis; COVID-19 identification; COVID-19 Serological Testing - standards; Emergency Service, Hospital; Fluorescence; Fluorescence immunoassay (FIA); Humans; Immunoassay; Italy - epidemiology; Nasopharynx - virology; Phosphoproteins - analysis; Rapid antigen diagnostic test; Reverse Transcriptase Polymerase Chain Reaction; SARS-CoV-2 - immunology; SARS-CoV-2 - isolation & purification; SARS-CoV-2 infection; Sensitivity and Specificity; Time Factors
• ISSN: 0166-0934; 1879-0984
• DOI: 10.1016/j.jviromet.2021.114201

•Development of ultra-rapid, SARS-CoV-2 diagnostic methods is crucial.•FREND™ COVID-19 Ag assay is a “3 min” test for SARS−COV-2 identification.•FREND™ FIA test showed high sensitivity and specificity in nasopharyngeal swabs. Viral RNA amplification by real-time RT-PCR still represents the gold standard for the detection of SARS-CoV-2, but the development of rapid, reliable and easy-to-perform diagnostic methods is crucial for public health, because of the need of shortening the time of result-reporting with a cost-efficient approach. The aim of our research was to assess the performance of FREND™ COVID-19 Ag assay (NanoEntek, South Korea) as a ultra-rapid frontline test for SARS-CoV-2 identification, in comparison with RT-PCR and another COVID-19 antigen fluorescence immunoassay (FIA). The qualitative FIA FREND™ test, designed to detect within 3 min the Nucleocapsid protein of SARS-CoV-2, was evaluated using nasopharyngeal swabs in Universal Transport Medium (UTM™, Copan Diagnostics Inc, US) from suspected COVID-19 cases who accessed the Emergency Room of the Ospedale Policlinico San Martino, Genoa, Liguria, Northwest Italy. Diagnostic accuracy was determined in comparison with SARS-CoV-2 RT-PCR and STANDARD F™ COVID-19 Ag FIA test (SD BIOSENSOR Inc., Republic of Korea). In November 2020, 110 nasopharyngeal samples were collected consecutively; 60 resulted RT-PCR positive. With respect to RT-PCR results, sensitivity and specificity of FREND™ COVID-19 Ag test were 93.3 % (95 % CI: 83.8−98.2) and 100 % (95 % CI: 92.9−100), respectively. FREND™and STANDARD F™ COVID-19 Ag FIA assays showed a concordance of 96.4 % (Cohen’s k = 0.93, 95 % CI: 0.86−0.99). FREND™ FIA test showed high sensitivity and specificity in nasopharyngeal swabs. The assay has the potential to become an important tool for an ultra-rapid identification of SARS-CoV-2 infection, particularly in situations with limited access to molecular diagnostics.