Sensitivity of rapid antigen tests against SARS-CoV-2 Omicron and Delta variants

• Type of Material: Article
• Authors: Anuradha Rao, Emory University; Adrianna Lynn Westbrook, Emory University; Leda C. Bassit, Emory University; Richard Parsons, Emory University; Eric Charles Fitts, Emory University; Morgan Greenleaf, Emory University; Kaleb benjamin McLendon, Emory University; Julie A. Sullivan, Emory University; William O'Sick, Emory Unviersity; Tyler Jon Baugh, Emory University; Heather Brittany Bowers, Emory University; Filipp Frank, Emory University; Ethan Wang, Emory University; Mimi Le, Emory University; Jennifer K Frediani, Emory University; Pavitra Roychoudhury, University of Washington; Alexander L. Greninger, University of Washington; Robert Jerris, Children's Healthcare of Atlanta; Nira R. Pollock, Harvard University; Eric Ortlund, Emory University; John D Roback, Emory University; Wilbur Lam, Emory University; Anne L. Piantadosi, Emory University
• Language: English
• Date: 2023-09-20
• Publisher: American Society for Microbiology
• Publication Version: Final Published Version
• Copyright Statement: © 2023 Rao et al.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): https://doi.org/10.1128/jcm.00138-23
• Title of Journal or Parent Work: Journal of Clinical Microbiology
• Volume: 61
• Issue: 10
• Start Page: e00138
• End Page: 23
• Grant/Funding Information: This work was supported by the National Institute of Biomedical Imaging and Bioengineering under the Atlanta Center for Microsystems Engineered Point-of-Care Technologies (ACME POCT). This work was supported by the NIBIB at the NIH under awards 3U54 EB027690-03S1, 3U54 EB027690-03S2, and 3U54 EB027690-04S1, and the National Center for Advancing Translational Sciences of the NIH under award UL1TR002378.
• Keywords: SARS-CoV-2; rapid antigen test
• Research Categories: Health Sciences, Epidemiology; Health Sciences, Public Health; Biology, Virology; Biology, Microbiology

Abstract

Rapid antigen tests (RATs) have become an invaluable tool for combating the COVID-19 pandemic. However, concerns have been raised regarding the ability of existing RATs to effectively detect emerging SARS-CoV-2 variants. We compared the performance of 10 commercially available, emergency use authorized RATs against the Delta and Omicron SARS-CoV-2 variants using both individual patient and serially diluted pooled clinical samples. The RATs exhibited lower sensitivity for Omicron samples when using PCR cycle threshold (CT) value (a rough proxy for RNA concentration) as the comparator. Interestingly, however, they exhibited similar sensitivity for Omicron and Delta samples when using quantitative antigen concentration as the comparator. We further found that the Omicron samples had lower ratios of antigen to RNA, which offers a potential explanation for the apparent lower sensitivity of RATs for that variant when using C T value as a reference. Our findings underscore the complexity in assessing RAT performance against emerging variants and highlight the need for ongoing evaluation in the face of changing population immunity and virus evolution.