Fighting SARS-CoV-2 with mouthwashes—study adds to evidence of efficacy
BADALONA, Spain: Mouthwashes that contain cetylpyridinium chloride (CPC) have been found to reduce by at least one thousand times the infectivity of SARS-CoV-2 in vitro. Researchers in Spain tested CPC-containing mouthwashes against variants of SARS-CoV-2, including the Alpha variant, and said that such mouth rinses could constitute a cost-effective measure to aid in the reduction of viral transmission.
In the study, the researchers pointed out that cases with a higher SARS-CoV-2 viral load in the saliva are associated with higher transmission rates of the virus. They said that, if proved effective in reducing the SARS-CoV-2 viral load, the use of easily obtainable at-home oral care products could represent a globally accessible and cost-effective measure to disrupt the viral transmission chain.
The study focused on the effect of the quaternary ammonium compound CPC, which has previously been shown to exhibit antiviral activity against viruses such as MERS-CoV and influenza viruses.
The researchers tested three Dentaid CPC-containing mouthwashes with different intended uses (VITAS Encías, 0.05% CPC, a daily mouthwash intended for use in people with delicate gums; PERIO AID Intensive Care, 0.05% CPC, intended for limited-term use in post-oral surgery patients and/or those undergoing periodontal treatment; and VITAS CPC Protect, 0.07% CPC, intended for daily use to prevent and reduce the formation of dental plaque).
The CPC-containing mouthwashes were compared with vehicles containing the same respective formulation without CPC, and it was found that they disrupted the integrity of the viral membrane and inhibited the entry of SARS-CoV-2 into target cells. “CPC-containing mouthwashes decreased more than a thousand times the infectivity of replication-competent SARS-CoV-2, were active in the presence of sterilised saliva, and were effective against SARS-CoV-2 variants,” the researchers wrote.
They continued: “CPC has antiviral activity against different variants of SARS-CoV-2, and this compound exerts its activity by blocking viral entry by inhibiting viral fusion on target cells. CPC acts by disrupting the integrity of the viral envelope, as previously shown for influenza virus […] and it equally affects distinct SARS-CoV-2 variants.”
Other chemical components that are found in popular over-the-counter mouthwashes, the researchers wrote, such as hydrogen peroxide and chlorhexidine, have shown limited activity against SARS-CoV-2.
The researchers further commented that additional studies should be conducted to assess whether CPC-containing mouthwashes are effective in decreasing viral load and infectivity of viruses found in the oral cavity of those infected with SARS-CoV-2. “If proven effective, CPC-containing mouthwashes should be active against those variants that pose a threat to vaccine efficacy, which may increase transmissibility rates and could even worsen clinical outcome,” they said.
“While brushing and rinsing are not a treatment or a way to fully protect an individual from infection, they may help to reduce transmission and slow the spread of the virus” – Dr Maria Ryan, Colgate-Palmolive
Dental Tribune International has previously reported on studies that showed the potential of toothpastes containing zinc or stannous fluoride, CPC mouthwashes and mouthwashes containing a mixture of the substances beta-cyclodextrin and Citrox to drastically reduce SARS-CoV-2 viral load in the oral cavity. Colgate-Palmolive last year began partnering with research institutes to study the effects of toothpastes and mouthwashes on SARS-CoV-2 viral load, and the company’s chief dental officer, Dr Maria Ryan, commented in a press release that the clinical results were promising. “While brushing and rinsing are not a treatment or a way to fully protect an individual from infection, they may help to reduce transmission and slow the spread of the virus, supplementing the benefit we get from wearing masks, social distancing and frequent hand-washing,” Ryan said.
The study, titled “Mouthwashes with CPC reduce the infectivity of SARS-CoV-2 variants in vitro”, was published online on 20 July 2021 in Journal of Dental Research, ahead of inclusion in an issue.