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Comparison of SARS-CoV-2 RT-PCR and BinaxNOW Rapid Antigen Tests During Omicron Surge
TAKE-HOME MESSAGE
- This single-center cross-sectional study compared the performance of a rapid antigen test (Abbott, BinaxNOW) with polymerase chain reaction (PCR) testing in 731 individuals presenting for COVID-19 testing in January 2022. PCR testing returned positive for 40.5% of patients; 65.2% of the patients in this group tested positive based on the antigen test, with 95.2% of patients testing positive on the antigen test when the PCR cycle threshold was below 30.
- Although effective in diagnosing infection at peak cycle threshold values, the authors indicate that repeat antigen testing for those suspected of having COVID-19, who were initially tested negative, may still be necessary. Additionally, compared with the tests using nasal swab samples, antigen tests performed with samples drawn from the cheek or throat were substantially inferior in detecting the virus.
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.
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.