Evaluating The Performance Characteristics of Five Lateral Flow Assays for The Detection of The SARS- CoV-2 Nucleocapsid Antigen

Abstract

Introduction: In response to the COVID-19 pandemic, lateral flow assays (LFAs) for the detection of SARS-CoV-2 antigen have been proposed as a complementary option to the more costly and time consuming reverse-transcriptase polymerase chain reaction (RT-PCR). We assessed five commercially available SARS-CoV-2 antigen detecting LFAs (ASSUT EUROPE (Rome, Italy), Besthree (Taizhou, China), Encode (Zhuhai, China), Fortress (Antrim UK), and Hughes Medical (Buckinghamshire, UK), using samples collected from hospitalised individuals with COVID-19 and compared these results against established RT-PCR assays with the aim of estimating test performance characteristics.Method: We performed a diagnostic accuracy study of the LFAs on 110 inpatients with confirmed COVID-19 and 75 COVID-19 negative control participants. Assay evaluation was performed using a modified version of each manufacturer’s protocol allowing for parallel testing of a single sample on multiple assays.Results: Half (46%, 51) of the patient cohort were in the higher risk age category (>70 years old). Community acquisition of SARS-CoV-2 accounted for 77% (85) of our positive cohort with the remaining 23% (25) resulting from nosocomial transmission. The sensitivity of the LFAs ranged from 64% (95% CI 53-73) to 76% (95% CI 65-85). Of the assays tested, Fortress performed best with a sensitivity of 76% (95% CI 65-85). Specificity based on testing SARS-CoV-2 volunteers was high across all assays with four of the five achieving 100%Conclusion: SARS-CoV-2 antigen detecting LFAs may complement RT-PCR testing to facilitate early diagnosis and provide community testing strategies for identification of patients with COVID-19, however we find suboptimal test performance characteristics across a range of commercially available manufacturers, below WHO and MHRA pre-set sensitivity performance thresholds. With such variation in sensitivity between LFAs and PCR testing and between assay brands, we advise caution in the deployment of LFAs outside of environments with clinical oversight.

Nanotechnology meets immunology towards a rapid diagnosis solution: the COVID-19 outbreak challenge

“…9,13,14 In this view, the development of simple and rapid LFA-based diagnostic tests for the direct detection of SARS-CoV-2, abbreviating the usual time window necessary for conventional diagnostic methods associated with the potential utilization at the POC, is exceedingly needed as a crucial weapon to fight against the COVID-19 pandemic. 1,9,11,15,21–23…”

“…9,13,14 In this view, the development of simple and rapid LFA-based diagnostic tests for the direct detection of SARS-CoV-2, abbreviating the usual time window necessary for conventional diagnostic methods associated with the potential utilization at the POC, is exceedingly needed as a crucial weapon to ght against the COVID-19 pandemic. 1,9,11,15,[21][22][23] Herein, we present all stages of the development of an LFAbased diagnostic immunoassay for directly detecting SARS-CoV-2, encompassing the in silico design of novel synthetic peptides with immunogenic epitopes inspired by the virus spike-protein, the production of high-affinity antibodies through semi-puried hyperimmune sera from rabbits, the synthesis of colloidal gold nanoparticles as optically active nanoprobes, their bioconjugation with the affinity biomolecules, which were all integrated into a nitrocellulose membrane strip, demonstrating effective recognition of COVID-19-infected patient sera.…”