Abstract
BackgroundReal-Time Reverse-Transcription Polymerase Chain Reaction (RT-PCR) is currently the only recommended diagnostic method for SARS-CoV-2. However, rapid immunoassays for SARS-CoV-2 antigen could significantly reduce the COVID-19 burden currently weighing on laboratories around the world.MethodsWe evaluated the performance of two rapid fluorescence immunoassays (FIAs), SOFIA SARS Antigen FIA (Quidel Corporation, San Diego, CA, USA) and STANDARD F COVID-19 Ag FIA (SD Biosensor Inc., Gyeonggi-do, Republic of Korea), which use an automated reader. The study used 64 RT-PCR characterized clinical samples (32 positive; 32 negative), which consisted of nasopharyngeal swabs in universal transport medium.ResultsOf the 32 positive specimens, all from patients within 5 days of symptom onset, the Quidel and SD Biosensor assays detected 30 (93.8%) and 29 (90.6%) samples, respectively. Among the 27 samples with high viral loads (Ct ≤ 25), the two tests had a sensitivity of 100%. Specificity was 96.9% for both kits.ConclusionThe high performance of the evaluated FIAs indicates a potential use as rapid and PCR-independent tools for COVID-19 diagnosis in early stages of infection. The excellent sensitivity to detect cases with viral loads above ~106 copies/mL (Ct values ≤ 25), the estimated threshold of contagiousness, suggests that the assays might serve to rapidly identify infective individuals.
Highlights
Since the declaration of the COVID-19 pandemic in March 2020, infection with the new SARS-CoV-2 has resulted in over 30 million confirmed cases and almost 1 million deaths worldwide, as of September 2020
We present the performance of two novel fluorescence immunoassays (FIAs) automated antigen detection systems in samples from COVID-19 patients presenting within 5 days of symptom onset
One of the main concerns about antigen-based tests is that these assays per se have a higher detection threshold than Reverse-Transcription Polymerase Chain Reaction (RT-PCR), they might miss cases with low viral replication during very early or late infections (World Health Organization, 2020c; Liotti et al, 2020)
Summary
Since the declaration of the COVID-19 pandemic in March 2020, infection with the new SARS-CoV-2 has resulted in over 30 million confirmed cases and almost 1 million deaths worldwide, as of September 2020 (https://COVID19.who.int). Rapid antigen detection tests (Ag-RDT) using immunochromatographic (ICT) or fluorescence immunoassays (FIAs) have recently become available; many of which are CE-IVD licensed and some have received FDA emergency use authorization (EUA) (www.finddx.org/COVID-19/pipeline) These tests are fast, easy to use and do not require highly trained personnel or sophisticated equipment. As previously suggested FIAs are highly specific and can reach remarkably high sensitivities, if applied in samples from early phases of infection or with high viral loads (Porte et al, 2020; Weitzel et al, 2020, Liotti et al, 2020) For this reason, they could complement RT-PCR testing by becoming a first line tool for rapid detection of infective individuals. We present the performance of two novel FIA automated antigen detection systems in samples from COVID-19 patients presenting within 5 days of symptom onset
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
