Antiviral effect of cetylpyridinium chloride on SARS-CoV-2 in patients with COVID-19: An Observational Study

Objectives: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the viral agent responsible for the COVID-19 pandemic and primarily invades the body through the oral cavity. Cetylpyridinium chloride (CPC), a widely used component of oral care products, has demonstrated antiviral effects against SARS-CoV-2; however, the clinical evidence remains limited. This study investigated the virucidal effects of oral CPC in patients with COVID-19 and its impact on reverse transcription polymerase chain reaction (RT-PCR) positivity. Methods: Thirty-four patients with COVID-19 were initially recruited after obtaining positive PCR test result. This study was conducted during a nationwide Delta-variant–driven epidemic characterized by high viral loads and enhanced transmissibility. Saliva was collected at seven predefined time points to assess the effects of CPC-containing tablets and mouthwash. Viral RNA levels and infectious viral titers were quantified using qRT-PCR and plaque assays. Sixteen patients with detectable SARS-CoV-2 RNA in baseline saliva samples who completed all scheduled samplings constituted the final analytical cohort. Results: During the Delta-variant–predominant period, CPC-containing tablets reduced both SARS-CoV-2 RNA levels and viral infectivity in saliva. In contrast, CPC-containing mouthwashes did not significantly reduce viral RNA levels compared to baseline samples. The RT-PCR positivity rates after CPC use varied according to the applied cycle threshold (Ct) cutoff values. Conclusions: CPC-containing tablets transiently decrease the SARS-CoV-2 salivary viral load and infectivity and may help reduce the risk of transmission in public settings. When CPC formulations are used prior to saliva-based PCR testing, the Ct cut-off values may require adjustment. Clinical significance: Despite challenges in conducting saliva-based clinical research in COVID-19 patients, this study provides clinical evidence supporting the antiviral efficacy of CPC formulations on salivary SARS-CoV-2 during the Delta-variant pandemic.