No Effect of Antiseptic Mouthwash/Gargling Solution on SARS-CoV-2 Load

Objectives: Objectives: During the COVID-19 pandemic, various preventive measures were introduced to reduce viral load. This randomized trial aimed to evaluate the impact of four over-the-counter antiseptic mouthwash/gargling solutions versus water on the critical threshold value (Ct) of SARS-CoV-2 load in unstimulated saliva, throat wash (gargle lavage) and oropharyngeal swab at baseline, day 7, and day 28.
Methods: Methods: This pilot study was a double-blinded, 5-arm, parallel-group, randomized controlled clinical trial for individuals testing positive for COVID-19 via Reverse Transcription quantitative Polymerase Chain Reaction (RT-qPCR). After obtaining consent, adults (≥18 years) meeting inclusion/exclusion criteria were randomly allocated to rinse for 28 days with either Control (Distilled water), CloSYS Ultra Sensitive, Oral-B Mouth Sore, Crest Pro-Health Multi-Protection, and Listerine Zero. Samples from unstimulated saliva, throat wash, and oropharyngeal swab were collected at baseline, and throat wash on days 7 and 28. Samples were transported to a BSL2+ laboratory for Ct value testing using RT-qPCR. Repeated measures proportional hazard models with triplicate Ct values for N1 and N2 primers compared each rinse to water, adjusting for mean pre-rinse baseline Ct value.
Results: Results: Of 54 participants, 49 finished the 28-day study period. The mean age was ~40 years. No significant differences or suggestive patterns were evident between rinses and control in Ct values of baseline post-rinse (P>0.38), day 7 (P>0.23), or day 28 (P>0.97) before correcting for interim analysis or multiple comparisons, meaning no mouthwash appeared to reduce SARS-CoV-2 load. The mean (standard deviation) change in Ct value from baseline pre- to post-rinse was -0.7 (0.6) across all groups.
Conclusions: Conclusion: There were no apparent changes in Ct values within rinses pre- and post-rinse or between rinses and water at any time.