From triplex to tetraplex: evaluation of the diagnostic accuracy of the new Roche Cobas Liat SARS-CoV-2, influenza A/B & RSV assay

Abstract

Rapid and accurate diagnostics of epidemic respiratory viruses are relevant for optimal care pathways. In this observational diagnostic accuracy study, the novel Cobas Liat assay (Roche Molecular Systems) was evaluated for the detection of SARSCoV-2, influenza A and B, and respiratory syncytial virus (RSV) in the clinical setting of Tampere University Hospital, Tampere, Finland. In addition, the added value of the tetraplex assay instead of two partially overlapping triplex assays (influenza A/B and SARS-CoV-2 or RSV) was assessed in the context of adult and pediatric emergency department (AED, PED) point-of-care (PoC) testing environments. A total of 315 clinical nasopharyngeal swab samples were analyzed. Diagnostic accuracy was evaluated against a molecular diagnostic reference. The evaluated Cobas Liat assay had sensitivities and specificities of 100% and 98.5% for influenza A, 100% and 99.7% for influenza B, 100% and 98.2% for SARS-CoV-2, and 100% and 97.0% for RSV, respectively. Among the index and reference tests, the Cobas Liat assay demonstrated the highest analytical sensitivity for influenza A, SARS-CoV-2, and RSV. No cross-reactivity with off-panel microbes was observed. With respect to clinical applicability, implementation of the evaluated tetraplex test would decrease double testing with two triplex tests in PED, likely decreasing costs and hands-on work. In AED, tetraplex testing would likely significantly increase the diagnostic yield for RSV, only rarely covered by PoC testing in AED. The evaluated Cobas Liat assay had excellent clinical and analytical accuracy, being highly suitable for PoC use but also for laboratory-based testing of influenza viruses, SARS-CoV-2, and RSV.