Reduced Relative Sensitivity of the Elecsys SARS-CoV-2 Antigen Assay in Saliva Compared to Nasopharyngeal Swabs

Microorganisms

Christoph Berger¹  Dominique L. Braun²  Thomas Scheier²  Barbara Hasse²  Peter W. Schreiber²  Roberto Buonomano³  Gerhard Eich⁴  Alain Rudiger⁵  Dagmar I. Keller⁶  Huldrych F. Günthard⁷  Alexandra Trkola⁷  Annette Audigé⁷  Michael Huber⁷  Jürg Böni⁷  Amapola Manrique⁷ 

[1] Division of Infectious Diseases and Hospital Epidemiology, University Children’s Hospital Zurich, 8032 Zurich, Switzerland;Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland;Division of Infectious Diseases and Hospital Hygiene, Spital Limmattal, 8952 Schlieren, Switzerland;Division of Infectious Diseases, Hospital Hygiene and Occupational Medicine, Stadtspital Triemli, 8063 Zurich, Switzerland;Division of Medicine, Spital Limmattal, 8952 Schlieren, Switzerland;Emergency Department, University Hospital Zurich, 8091 Zurich, Switzerland;Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland;

关键词: SARS-CoV-2;    saliva;    RT-PCR;    antigen assay;   

DOI  :  10.3390/microorganisms9081700

来源: DOAJ

【 摘 要 】

Early identification and isolation of SARS-CoV-2-infected individuals is central to contain the COVID-19 pandemic. Nasopharyngeal swabs (NPS) serve as a specimen for detection by RT-PCR and rapid antigen screening tests. Saliva has been confirmed as a reliable alternative specimen for RT-PCR and has been shown to be valuable for diagnosing children and in repetitive mass testing due to its non-invasive collection. Combining the advantages of saliva with those of antigen tests would be highly attractive to further increase test capacities. Here, we evaluated the performance of the Elecsys SARS-CoV-2 Antigen assay (Roche) in RT-PCR-positive paired NPS and saliva samples (N = 87) and unpaired NPS (N = 100) with confirmed SARS-CoV-2 infection (Roche cobas SARS-CoV-2 IVD test). We observed a high positive percent agreement (PPA) of the antigen assay with RT-PCR in NPS, reaching 87.2% across the entire cohort, whereas the overall PPA for saliva was insufficient (40.2%). At Ct values ≤ 28, PPA were 100% and 91.2% for NPS and saliva, respectively. At lower viral loads, the sensitivity loss of the antigen assay in saliva was striking. At Ct values ≤ 35, the PPA for NPS remained satisfactory (91.5%), whereas the PPA for saliva dropped to 46.6%. In conclusion, saliva cannot be recommended as a reliable alternative to NPS for testing with the Elecsys Anti-SARS-CoV-2 Antigen assay. As saliva is successfully used broadly in combination with RT-PCR testing, it is critical to create awareness that suitability for RT-PCR cannot be translated to implementation in antigen assays without thorough evaluation of each individual test system.

【 授权许可】

Unknown