Evaluation of a new molecular test for the detection of SARS-CoV-2 nucleic acid in salivary samples

Background: Molecular testing is considered the gold stan- dard for the detection of SARS-CoV-2. This study aimed to compare the performance of the P742H SARS-CoV-2 Nucleic Acid Multiplex Detection Kit in salivary samples, with respect to the 732HF Novel Coronavirus (2019-nCoV) Nucleic Acid Detection Kit and the TaqPath COVID-19 CE- IVD RT-PCR Kit, used at University-Hospital of Padova, Italy. Methods: One hundred twenty-four salivary samples self- collected by healthcare workers (HCW) during the screen- ing program at University-Hospital of Padova, Italy, from Oct to Nov 2022, were included in the study. RNA extrac- tion was performed by Viral DNA and RNA Extraction Kit (Technogenetics, Lodi, Italy) and amplification by P742H and 732HF (Technogenetics, Lodi, Italy). RNA was extract- ed using MagNa Pure 96 DNA and Viral NA Small Volume Kit (Roche, Switzerland) for TaqPath analysis (Thermo Fisher Scientific, USA). Results: 94 samples were positive at P742H, while 30 were negative; for 732HF, 96 samples were positive, while 28 were negative, with an overall agreement of 97.5% (Cohen’s = 0.930, p < 0.001). TaqPath gave 95 positive samples, and 29 negative results, with an overall agree- ment of 100% (Cohen’s = 1.0, p < 0.001) with respect to P742H, and 97.5% (Cohen’s = 0.931, p < 0.001) with respect to 732HF. Comparing cycle threshold (Ct) between the P742H and 732HF, no statistically significant differences were found (p = n.s.). Conclusion: The P742H method proved better perform- ances than 732HF for salivary samples, both presenting the same amplification time. In addition, P742H results were comparable to those obtained through the high- throughput method TaqPath.