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 1.6×104-4.3×104 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%.
Performance characteristics of a rapid SARS-CoV-2 antigen detection assay at a public plaza testing site in San Francisco
Genay Pilarowski, Paul Lebel, Sara Sunshine, Jamin Liu, Emily Crawford, Carina Marquez, Luis Rubio, Gabriel Chamie, Jackie Martinez, James Peng, Douglas Black, Wesley Wu, John Pak, Matthew T. Laurie, Diane Jones, Steve Miller, Jon Jacobo, Susana Rojas, Susy Rojas, Robert Nakamura, Valerie Tulier-Laiwa, Maya Petersen, Diane V. Havlir, The CLIAHUB Consortium, Joseph DeRisi