Comparison of SARS-CoV-2 RT-PCR and BinaxNOW Rapid Antigen Tests During Omicron Surge
abstract
This abstract is available on the publisher's site.
Access this abstract nowBACKGROUND
SARS-CoV-2 rapid antigen tests are an important public health tool.
OBJECTIVE
To evaluate field performance of the BinaxNOW rapid antigen test (Abbott) compared with reverse transcriptase polymerase chain reaction (RT-PCR) for detecting infection with the Omicron variant of SARS-CoV-2.
DESIGN
Cross-sectional surveillance study.
SETTING
Free, walk-up, outdoor, urban community testing and vaccine site led by Unidos en Salud, serving a predominantly Latinx community highly impacted by COVID-19.
PARTICIPANTS
Persons seeking COVID-19 testing in January 2022.
MEASUREMENTS
Simultaneous BinaxNOW and RT-PCR from nasal, cheek, and throat swabs, including cycle threshold (Ct) measures; a lower Ct value is a surrogate for higher amounts of virus.
RESULTS
Among 731 persons tested with nasal swabs, there were 296 (40.5%) positive results on RT-PCR; 98.9% were the Omicron variant. BinaxNOW detected 95.2% (95% CI, 91% to 98%) of persons who tested positive on RT-PCR with a Ct value below 30, 82.1% (CI, 77% to 87%) of those who tested positive on RT-PCR with a Ct value below 35, and 65.2% (CI, 60% to 71%) of all who were positive on RT-PCR. Among 75 persons with simultaneous nasal and cheek swabs, BinaxNOW using a cheek swab failed to detect 91% (20 of 22) of specimens that were positive on BinaxNOW with a nasal swab. Among persons with simultaneous nasal and throat swabs who were positive on RT-PCR with a Ct value below 30, 42 of 49 (85.7%) were detected by nasal BinaxNOW, 23 of 49 (46.9%) by throat BinaxNOW, and 44 of 49 (89.8%) by either.
LIMITATION
Participants were a cross-sectional sample from a community-based sentinel surveillance site, precluding study of viral or symptom dynamics.
CONCLUSION
BinaxNOW detected persons with high SARS-CoV-2 levels during the Omicron surge, enabling rapid responses to positive test results. Cheek or throat swabs should not replace nasal swabs. As currently recommended, high-risk persons with an initial negative BinaxNOW result should have repeated testing.
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Additional Info
Disclosure statements are available on the authors' profiles:
Comparison of SARS-CoV-2 Reverse Transcriptase Polymerase Chain Reaction and BinaxNOW Rapid Antigen Tests at a Community Site During an Omicron Surge: A Cross-Sectional Study
Ann. Intern. Med 2022 May 01;175(5)682-690, J Schrom, C Marquez, G Pilarowski, CY Wang, A Mitchell, R Puccinelli, D Black, S Rojas, S Ribeiro, V Tulier-Laiwa, J Martinez, J Payan, S Rojas, D Jones, D Martinez, R Nakamura, G Chamie, V Jain, M Petersen, J DeRisi, D HavlirFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
This study evaluated the performance of BinaxNOW rapid antigen test compared with RT-PCR for detection of infection with the Omicron variant of SARS-CoV-2. The study was conducted on 731 people who sought out testing at a free, outdoor, walk-up community testing and vaccine site in January 2022. Out of the 731 people tested with nasal swabs, 40.5% of people testing positive on RT-PCR, with most (98.9%) having the Omicron variant. BinaxNOW rapid antigen test was positive in 95.2% of these patients who had a cycle threshold value below 30, which is a surrogate for higher viral load. The correlation between positive RT-PCR and positive BinaxNow rapid antigen decreased as the cycle threshold got higher (less viral load). BinaxNOW rapid antigen test was positive in 82.1% of people who tested positive on RT-PCR, with a cycle threshold value below 35, and 65.2% of all who were positive on RT-PCR. This study demonstrated that BinaxNOW detected people with high SARS-CoV-2 viral levels during the Omicron surge. The study also showed that simultaneous cheek or throat swabs should not replace nasal swabs.