Use of an antiviral mouthwash as a barrier measure in the SARS-CoV-2 transmission in adults with asymptomatic to mild COVID-19: a multicentre, randomized, double-blind controlled trial

OBJECTIVES: To determine if commercially available mouthwash with β-cyclodextrin and citrox (bioflavonoids) (CDCM) could decrease the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) salivary viral load. METHODS: In this randomized controlled trial, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) PCR-positive patients aged 18–85 years with asymptomatic to mild coronavirus disease 2019 (COVID-19) symptoms for <8 days were recruited. A total of 176 eligible patients were randomly assigned (1:1) to CDCM or placebo. Three rinses daily were performed for 7 days. Saliva sampling was performed on day 1 at 09.00 (T1), 13.00 (T2) and 18.00 (T3). On the following 6 days, one sample was taken at 15.00. Quantitative RT-PCR was used to detect SARS-CoV-2. RESULTS: The intention-to-treat analysis demonstrated that, over the course of 1 day, CDCM was significantly more effective than placebo 4 hours after the first dose (p 0.036), with a median percentage (log(10) copies/mL) decrease T1–T2 of –12.58% (IQR –29.55% to –0.16%). The second dose maintained the low median value for the CDCM (3.08 log(10) copies/mL; IQR 0–4.19), compared with placebo (3.31 log(10) copies/mL; IQR 1.18–4.75). At day 7, there was still a greater median percentage (log(10) copies/mL) decrease in salivary viral load over time in the CDCM group (–58.62%; IQR –100% to –34.36%) compared with the placebo group (–50.62%; IQR –100% to –27.66%). These results were confirmed by the per-protocol analysis. CONCLUSIONS: This trial supports the relevance of using CDCM on day 1 (4 hours after the initial dose) to reduce the SARS-CoV-2 viral load in saliva. For long-term effect (7 days), CDMC appears to provide a modest benefit compared with placebo in reducing viral load in saliva.