COVID-19: Rapid Antigen detection for SARS-CoV-2 by lateral flow assay: a national systematic evaluation for mass-testing

UK COVID-19 Lateral Flow Oversight Team,; Peto, T.

Background: New lateral flow device (LFD) viral antigen immunoassays have been developed by commercial and research organisations around the world as diagnostic tests for SARS-CoV-2 infection. To support decisions by the UK Government on potential scale-up of mass population testing, we have at their request evaluated the diagnostic performance of a significant number of point-of-care rapid SARS-CoV-2 LFDs. Methods: 132 LFDs were initially reviewed by a Department of Health and Social Care team, part of the UK government, from which 64 were selected for further evaluation. Standardised laboratory evaluations, and for those that met the published criteria, field testing in the Falcon-C19 research study and UK pilots were performed (UK COVID-19 testing centres, hospital, schools, armed forces). Results: 4/64 LFDs so far have desirable performance characteristics from independent laboratory studies and early preliminary field evaluations (Orient Gene, Deepblue and Innova SARS-CoV-2 Antigen Rapid Qualitative Test), of which one underwent extended clinical assessment in field studies (Innova). 8951 Innova LFD tests were performed with a kit failure rate of 5.6% (502/8951, 95% CI: 5.1-6.1), false positive rate of 0.32% (22/6954, 95% CI: 0.20-0.48) and a viral antigen detection/sensitivity (using RNA RT-PCR as a proxy for the presence of antigen) of 78.8% when performed by laboratory scientists (156/198, 95% CI 72.4-84.3). Sensitivity was significantly lower when testing was undertaken by non-experts with limited initial training Interpretation: Several LFDs have promising performance characteristics for mass population testing and can be used to identify infectious positive individuals. The Innova LFD shows good viral antigen detection/sensitivity with excellent specificity, although kit failure rates and the impact of training are potential issues. These results support the expanded evaluation of LFDs, and assessment of greater access to testing on COVID-19 transmission. Funding: Department of Health and Social Care. University of Oxford. Public Health England Porton Down, Manchester University NHS Foundation Trust, National Institute of Health Research.