Analysis of seven SARS-CoV-2 rapid antigen tests in detecting omicron (B.1.1.529) versus delta (B.1.617.2) using cell culture supernatants and clinical specimens

• Published in: Infection 2023-02, Vol.51 (1), p.239-245
• Main Authors: Jungnick, Sabrina, Hobmaier, Bernhard, Paravinja, Natali, Mautner, Lena, Hoyos, Mona, Konrad, Regina, Haase, Maren, Baiker, Armin, Eberle, Ute, Bichler, Magdalena, Treis, Bianca, Okeyo, Mercy, Streibl, Barbara, Wimmer, Clara, Hepner, Sabrina, Sprenger, Annika, Berger, Carola, Weise, Laura, Dangel, Alexandra, Ippisch, Siegfried, Jonas, Walter, Wildner, Manfred, Liebl, Bernhard, Ackermann, Nikolaus, Sing, Andreas, Fingerle, Volker
• Format: Article
• Language: English
• Subjects: Antigens; Brief Report; Cell culture; Cell Culture Techniques; COVID-19; COVID-19 - diagnosis; COVID-19 diagnostic tests; Dilution; Family Medicine; General Practice; Humans; Infectious Diseases; Internal Medicine; Medicine; Medicine & Public Health; Polymerase chain reaction; Reverse transcription; Ribonucleic acid; RNA; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Transport media; Viral diseases
• ISSN: 0300-8126; 1439-0973; 1439-0973
• DOI: 10.1007/s15010-022-01844-5

Purpose Omicron is rapidly spreading as a new SARS-CoV-2 variant of concern (VOC). The question whether this new variant has an impact on SARS-CoV-2 rapid antigen test (RAT) performance is of utmost importance. To obtain an initial estimate regarding differences of RATs in detecting omicron and delta, seven commonly used SARS-CoV-2 RATs from different manufacturers were analysed using cell culture supernatants and clinical specimens. Methods For this purpose, cell culture-expanded omicron and delta preparations were serially diluted in Dulbecco’s modified Eagle’s Medium (DMEM) and the Limit of Detection (LoD) for both VOCs was determined. Additionally, clinical specimens stored in viral transport media or saline ( n  = 51) were investigated to complement in vitro results with cell culture supernatants. Ct values and RNA concentrations were determined via quantitative reverse transcription polymerase chain reaction (RT-qPCR). Results The in vitro determination of the LoD showed no obvious differences in detection of omicron and delta for the RATs examined. The LoD in this study was at a dilution level of 1:1,000 (corresponding to 3.0—5.6 × 10 6 RNA copies/mL) for tests I–V and at a dilution level of 1:100 (corresponding to 3.7—4.9 × 10 7 RNA copies/mL) for tests VI and VII. Based on clinical specimens, no obvious differences were observed between RAT positivity rates when comparing omicron to delta in this study setting. Overall positivity rates varied between manufacturers with 30–81% for omicron and 42–71% for delta. Test VII was only conducted in vitro with cell culture supernatants for feasibility reasons. In the range of Ct