Evaluation of the performance of rapid antigen tests to detect emerging SARS-CoV-2 variants and correlation with viral culture positivity

Disclaimer: The views expressed in this article are those of the author and do not necessarily reflect the official policy or position of the Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Uniformed Services University of the Health Sciences (USU), Departments of the Navy, Army, or Air Force, the Department of Defense, Defense Health Agency, nor the U.S. Government. Source of support: This work was supported by the Coronavirus Aid, Relief, and Economic Security (CARES) Act and conducted by the DoD’s JPEO-CBRND in collaboration with the Defense Health Agency. The EPICC study was supported by the Defense Health Program (HU00012020067) and the NIAID (HU00011920111). Human subject research protections: The investigators have adhered to the policies for protection of human subjects as prescribed in 45 CFR 46. Copyright statement: Some authors are military service members and employees of the U.S. Government. This work was prepared as part of their official duties. Title 17 U.S.C. §105 provides that “Copyright protection under this title is not available for any work of the United States Government”. Title 17 U.S.C. §101 defines a U.S. Government work as a work prepared by a military service member or employee of the U.S. Government as part of that person’s official duties. EVALUATION OF THE PERFORMANCE OF RAPID ANTIGEN TESTS TO DETECT EMERGING SARS-COV-2 VARIANTS AND CORRELATION WITH VIRAL CULTURE POSITIVITY Heather Poeck-Goux1, Jennetta Green1, Andrew Wilson1, Shanmuga Sozhamannan2,3, Mark Simons4, David Tribble4, Brian Agan4,5, Timothy Burgess4, Stephanie A. Richard4,5, Anthony Fries6, Simon D. Pollett, MBBS4,5, Jason Cox7, Robert Deans7, Joseph Walish7, Darci R. Smith1 1Microbiology and Immunology Department, Biological Defense Research Directorate, Naval Medical Research Command, Ft. Detrick, MD, USA, 2Joint Program Executive Office for Chemical, Biological, Radiological and Nuclear Defense (JPEO-CBRND), Joint Project Lead for CBRND
RITM0040473
Diagnostic testing has been critical to identify SARS-CoV-2 infected individuals, reducing transmission, and informing public health infection control measures. Antigen-based rapid diagnostic tests (ag-RDTs) provide timely results, are simple to use, and are less expensive than molecular assays such as reverse transcriptase polymerase chain reaction (RT-PCR). It is unclear how new variants of SARS-CoV-2 may impact the performance of ag-RDTs. Furthermore, recent studies suggest that antigen-based testing may align better with virus culture-based results (a proxy of contagiousness) compared to RT-PCR. In this study, we (1) assessed the performance of antibodies and ag-RDTs to detect a range of SARS-CoV-2 variants, including the Omicron variant and (2) determined if ag-RDTs results correlate with culture positivity. We found that the ag-RDTs demonstrated minor differences in sensitivity for all SARS-CoV-2 variants. Moderate to high sensitivity of ag-RDTs was observed when compared to swab PCR positivity and all assays were positive for at least one swab per variant. Ag-RDT sensitivity against PCR appeared to be inversely correlated with detection of viable virus whereas the Abbott BinaxNOW COVID-19 ag-RDT results correlated most strongly with culture positivity, while it was found to detect the lowest percent of PCR-positive swabs among the three ag-RDTs evaluated. Furthermore, we noted N mutations did not affect antigen binding kinetics in a further set of diagnostic antibodies used for other ag-RDT internal development. Collectively, our results demonstrate that commercially available ag-RDTs may offer ongoing sensitivity to detect emerging variants and offer the prospect of predicting case transmissibility risk. However, future studies are needed to define the agreement between ag-RDTs positivity, swab culture positivity, and transmissibility risk.