Comparative evaluation of STANDARD™ M10 Flu/RSV/SARS-CoV-2 and Savanna® Respiratory Viral Panel-4 assays for the rapid molecular diagnosis of influenza A/B virus, respiratory syncytial virus and SARS-CoV-2

Abstract

Background: The occurrence of respiratory infections caused by seasonal viruses influenza A/B, RSV and SARS-CoV-2 has increased the demand for rapid diagnostic assays. Comparative performance data of such assays is required.

Methods: In this retrospective study, clinical samples were tested with the STANDARD™ M10 Flu/RSV/SARS-CoV-2 test and the novel Savanna® Respiratory Viral Panel-4 tests, with Xpert® Xpress SARS-CoV-2/Flu/RSV as the reference. All three are RT-PCR tests suitable for point-of-care testing. Discordant results on the Savanna assay were retested with a new research-use-only protocol. Serial dilution testing for all three was performed with an external control.

Results: A total of 141 clinical samples, including 106 specimens positive for at least one virus, were analyzed. The M10 assay showed sensitivities of 100 %, 95.7 %, 97.1 % and 97.0 % for influenza A, B, RSV and SARS-CoV-2, respectively. The Savanna assay showed sensitivities of 92.6 %, 95.7 %, 100 % and 90.9 %. Both assays exhibited high specificity (≥99 %), except for the Savanna assay's lower specificity for RSV (94.2 %) and SARS-CoV-2 (94.3 %). Savanna had a higher retest rate (5.0 %), while M10 produced only conclusive results. Serial dilution testing showed that Xpert detected three viruses more effectively than the other assays.

Conclusion: Both M10 and Savanna performed well for influenza A/B, but M10 was superior for RSV and SARS-CoV-2 due to false positives with Savanna. The new Savanna protocol showed promise, but further studies are required to confirm these findings. Xpert assay was the most sensitive for detecting low viral amounts.

Keywords: Influenza A/B; Point-of-care-test; RSV; RT-PCR; Respiratory infections; SARS-CoV-2; STANDARD M10; Savanna.