Clinical and laboratory evaluation of SARS-CoV-2 lateral flow assays for use in a national COVID-19 seroprevalence surveyMore about Open Access at the Crick
Authors listBarnaby Flower Jonathan C Brown Bryony Simmons Maya Moshe Rebecca Frise Rebecca Penn Ruthiran Kugathasan Claire Petersen Anna Daunt Deborah Ashby Steven Riley Christina Joanne Atchison Graham P Taylor Sutha Satkunarajah Lenny Naar Robert Klaber Anjna Badhan Carolina Rosadas Maryam Khan Natalia Fernandez Macià Sureda-Vives Hannah M Cheeseman Jessica O'Hara Gianluca Fontana Scott JC Pallett Michael Rayment Rachael Jones Luke SP Moore Myra O McClure Peter Cherepanov Richard Tedder Hutan Ashrafian Robin Shattock Helen Ward Ara Darzi Paul Elliot Wendy S Barclay Graham S Cooke
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Background. Accurate antibody tests are essential to monitor the SARS-CoV-2 pandemic. Lateral flow immunoassays (LFIAs) can deliver testing at scale. However, reported performance varies, and sensitivity analyses have generally been conducted on serum from hospitalised patients. For use in community testing, evaluation of finger-prick self-tests, in non-hospitalised individuals, is required.
Methods. Sensitivity analysis was conducted on 276 non-hospitalised participants. All had tested positive for SARS-CoV-2 by reverse transcription PCR and were ≥21 days from symptom onset. In phase I, we evaluated five LFIAs in clinic (with finger prick) and laboratory (with blood and sera) in comparison to (1) PCR-confirmed infection and (2) presence of SARS-CoV-2 antibodies on two ‘in-house’ ELISAs. Specificity analysis was performed on 500 prepandemic sera. In phase II, six additional LFIAs were assessed with serum.
Findings. 95% (95% CI 92.2% to 97.3%) of the infected cohort had detectable antibodies on at least one ELISA. LFIA sensitivity was variable, but significantly inferior to ELISA in 8 out of 11 assessed. Of LFIAs assessed in both clinic and laboratory, finger-prick self-test sensitivity varied from 21% to 92% versus PCR-confirmed cases and from 22% to 96% versus composite ELISA positives. Concordance between finger-prick and serum testing was at best moderate (kappa 0.56) and, at worst, slight (kappa 0.13). All LFIAs had high specificity (97.2%–99.8%).
Interpretation. LFIA sensitivity and sample concordance is variable, highlighting the importance of evaluations in setting of intended use. This rigorous approach to LFIA evaluation identified a test with high specificity (98.6% (95%CI 97.1% to 99.4%)), moderate sensitivity (84.4% with finger prick (95% CI 70.5% to 93.5%)) and moderate concordance, suitable for seroprevalence surveys.
Issue number 12