Randomized clinical trial to assess the impact of oral intervention with cetylpyridinium chloride to reduce salivary SARS-CoV-2 viral load.

AIM: Aerosols released from the oral cavity help spread the SARS-CoV-2 virus. The use of a mouthwash formulated with an antiviral agent could reduce the viral load in saliva, helping to lower the spread of the virus. The aim of this study was to assess the efficacy of a mouthwash with 0.07% cetylpyridinium chloride (CPC) to reduce the viral load in the saliva of Coronavirus disease 2019 (COVID-19) patients. MATERIALS AND METHODS: In this multi-centre, single-blind, randomized, parallel group clinical trial, 80 COVID-19 patients were enrolled and randomized to two groups, namely test (n = 40) and placebo (n = 40). Saliva samples were collected at baseline and 2 h after rinsing. The samples were analysed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and an enzyme-linked immunosorbent assay test specific for the nucleocapsid (N) protein of SARS-CoV-2. RESULTS: With RT-qPCR, no significant differences were observed between the placebo group and the test group. However, 2 h after a single rinse, N protein concentration in saliva was significantly higher in the test group, indicating an increase in lysed virus. CONCLUSIONS: The use of 0.07% CPC mouthwash induced a significant increase in N protein detection in the saliva of COVID-19 patients. Lysis of the virus in the mouth could help reduce the transmission of SARS-CoV-2. However, more studies are required to prove this.

Cetylpyridinium chloride-containing mouthwashes reduce in vitro SARS-CoV-2 infectivity

Oral mouthwashes decrease the infectivity of several respiratory viruses including SARS-CoV-2. However, the precise agents with antiviral activity present in these oral rinses and their exact mechanism of action remain unknown. Here we show that Cetylpyridinium chloride (CPC), a quaternary ammonium compound present in many oral mouthwashes, reduces SARS-CoV-2 infectivity by inhibiting the viral fusion step with target cells after disrupting the integrity of the viral envelope. We also found that CPC-containing mouth rinses decreased more than a thousand times the infectivity of SARS-CoV-2 in vitro, while the corresponding vehicles had no effect. This activity was effective for different SARS-CoV-2 variants, including the B.1.1.7 variant, predominant in UK, also in the presence of sterilized saliva. CPC-containing mouth rinses could therefore represent a cost-effective measure to reduce SARS-CoV-2 infectivity in saliva, aiding to reduce viral transmission from infected individuals regardless of the variants they are infected with.