Performance characteristics of a rapid SARS-CoV-2 antigen detection assay at a public plaza testing site in San Francisco

• Published in: medRxiv : the preprint server for health sciences
• Main Authors: Pilarowski, Genay, Lebel, Paul, Sunshine, Sara, Liu, Jamin, Crawford, Emily, Marquez, Carina, Rubio, Luis, Chamie, Gabriel, Martinez, Jackie, Peng, James, Black, Douglas, Wu, Wesley, Pak, John, Laurie, Matthew T, Jones, Diane, Miller, Steve, Jacobo, Jon, Rojas, Susana, Rojas, Susy, Nakamura, Robert, Tulier-Laiwa, Valerie, Petersen, Maya, Havlir, Diane V, DeRisi, Joseph
• Format: Journal Article
• Language: English
• Published: United States 12.11.2020
• Subjects: COVID-19; Rapid Antigen Test; SARS-CoV-2; Point of Care testing
• DOI: 10.1101/2020.11.02.20223891

We evaluated the performance of the Abbott BinaxNOW™ Covid-19 rapid antigen test to detect virus among persons, regardless of symptoms, at a public plaza site of ongoing community transmission. Titration with cultured clinical SARS-CoV-2 yielded a human observable threshold between 1.6×10 -4.3×10 viral RNA copies (cycle threshold (Ct) of 30.3-28.8 in this assay). Among 878 subjects tested, 3% (26/878) were positive by RT-PCR, of which 15/26 had a Ct<30, indicating high viral load. 40% (6/15) of Ct<30 were asymptomatic. Using this Ct<30 threshold for Binax-CoV2 evaluation, the sensitivity of the Binax-CoV2 was 93.3% (14/15), 95% CI: 68.1-99.8%, and the specificity was 99.9% (855/856), 95% CI: 99.4-99.9%.