Evaluation of the Efficacy of Mouth Rinses With Commercial Mouthwashes to Decrease SARS-CoV-2 Viral Load in Saliva

As no curative treatment for SARS-CoV-2 is currently available, most public health measures to contain the pandemic are based on preventing the spread of the pathogen. The virus is transmitted by the respiratory route and by direct contact with contaminated surfaces and subsequent contact with nasal, oral or ocular mucosa. Although patients with symptomatic coronavirus disease 2019 (COVID-19) have been the main source of transmission, observations suggest that asymptomatic and incubating patients also have the ability to transmit SARS-CoV-2. Angiotensin II converting enzyme (ACE2) is the main cellular receptor for SARS-CoV-2, which interacts with the spike protein to facilitate its entry. ACE2 receptors are highly expressed in the oral cavity and present at high levels in oral epithelial cells. The mean expression of ACE2 was higher in the tongue compared to that in other oral tissues and it has been found to be higher in the minor salivary glands than in the lungs. These findings strongly suggest that the oral cavity and specifically the saliva may be a high-risk route for SARS-CoV-2 infection. Thus, strategies reducing salivary viral load could contribute to reduce the risk of transmission. Furthermore, studies using macaques as animal models have shown that SARS-CoV persists for two days in oral mucous membranes before its diffusion to the lower respiratory tract. This offers an interesting preventive and therapeutic window of opportunity for the control of this disease. For this reason, the use of mouthwashes with antiseptics that have virucidal activity can be a simple preventive strategy that could easily be applied both by infected patients before being examined by sanitary personnel and in the general population. This study is a multi-centered, blinded, parallel-group, placebo-controlled randomised clinical trial that tests the effect of three different mouthwashes (chlorhexidine 0,12%, chlorhexidine 0,2%, and Cymenol -ZnCl2) in the salivary viral load of SARS-CoV-2 measured by qPCR at three different timepoints. A fourth group of patients using a distilled water mouth rinse is used as a control. Viral particles per ml of saliva are quantified at baseline and 5, 15 and 60 minutes after a 1-minute mouth rinse with the antiseptic or water. The study aims to test whether any of these standard oral antiseptics appear to diminish viral load in saliva and could therefore be used as a strategy to reduce transmission risk in clinical and social settings.