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Reduced Relative Sensitivity of the Elecsys SARS-CoV-2 Antigen Assay in Saliva Compared to Nasopharyngeal Swabs.
Audigé, Annette; Böni, Jürg; Schreiber, Peter W; Scheier, Thomas; Buonomano, Roberto; Rudiger, Alain; Braun, Dominique L; Eich, Gerhard; Keller, Dagmar I; Hasse, Barbara; Berger, Christoph; Günthard, Huldrych F; Manrique, Amapola; Trkola, Alexandra; Huber, Michael.
  • Audigé A; Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland.
  • Böni J; Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland.
  • Schreiber PW; Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland.
  • Scheier T; Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland.
  • Buonomano R; Division of Infectious Diseases and Hospital Hygiene, Spital Limmattal, 8952 Schlieren, Switzerland.
  • Rudiger A; Division of Medicine, Spital Limmattal, 8952 Schlieren, Switzerland.
  • Braun DL; Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland.
  • Eich G; Division of Infectious Diseases, Hospital Hygiene and Occupational Medicine, Stadtspital Triemli, 8063 Zurich, Switzerland.
  • Keller DI; Emergency Department, University Hospital Zurich, 8091 Zurich, Switzerland.
  • Hasse B; Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland.
  • Berger C; Division of Infectious Diseases and Hospital Epidemiology, University Children's Hospital Zurich, 8032 Zurich, Switzerland.
  • Günthard HF; Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland.
  • Manrique A; Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland.
  • Trkola A; Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland.
  • Huber M; Institute of Medical Virology, University of Zurich, 8057 Zurich, Switzerland.
Microorganisms ; 9(8)2021 Aug 10.
Article in English | MEDLINE | ID: covidwho-1348674
ABSTRACT
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.
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Full text: Available Collection: International databases Database: MEDLINE Type of study: Cohort study / Diagnostic study / Experimental Studies / Observational study / Prognostic study Language: English Year: 2021 Document Type: Article Affiliation country: Microorganisms9081700

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Full text: Available Collection: International databases Database: MEDLINE Type of study: Cohort study / Diagnostic study / Experimental Studies / Observational study / Prognostic study Language: English Year: 2021 Document Type: Article Affiliation country: Microorganisms9081700