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Certain mouthwashes and oral antiseptics may inactivate human coronaviruses, and help reduce the spread of SARS-CoV-2 that causes COVID-19, according to a study.
The findings, published in the Journal of Medical Virology, indicate that some of these products might be useful for reducing the viral load, or amount of virus, in the mouth after infection.
The researchers from the Penn State College of Medicine in the United States tested several oral and nasopharyngeal rinses in a laboratory setting for their ability to inactivate human coronaviruses, which are similar in structure to SARS-CoV-2.
The products evaluated include a 1 per cent solution of baby shampoo, a neti pot, peroxide sore-mouth cleansers, and mouthwashes.
The team found that several of the nasal and oral rinses had a strong ability to neutralise human coronavirus, which suggests that these products may have the potential to reduce the amount of virus spread by people who are COVID-19-positive.
"While we wait for a vaccine to be developed, methods to reduce transmission are needed," said Craig Meyers, a professor at Penn State College of Medicine.
"The products we tested are readily available and often already part of people's daily routines," Meyers said.
The researchers used a test to replicate the interaction of the virus in the nasal and oral cavities with the rinses and mouthwashes.
Nasal and oral cavities are major points of entry and transmission for human coronaviruses.
They treated solutions containing a strain of human coronavirus, which served as a readily available and genetically similar alternative for SARS-CoV-2, with the baby shampoo solutions, various peroxide antiseptic rinses and various brands of mouthwash.
The researchers allowed the solutions to interact with the virus for 30 seconds, one minute and two minutes, before diluting the solutions to prevent further virus inactivation.
According to Meyers, the outer envelopes of the human coronavirus tested and SARS-CoV-2 are genetically similar so the research team hypothesises that a similar amount of SARS-CoV-2 may be inactivated upon exposure to the solution.
To measure how much virus was inactivated, the researchers placed the diluted solutions in contact with cultured human cells.
They counted how many cells remained alive after a few days of exposure to the viral solution and used that number to calculate the amount of human coronavirus that was inactivated as a result of exposure to the mouthwash or oral rinse that was tested.
The 1 per cent baby shampoo solution, which is often used by head and neck doctors to rinse the sinuses, inactivated greater than 99.9 per cent of human coronavirus after a two-minute contact time.
Several of the mouthwash and gargle products also were effective at inactivating the infectious virus, the researchers said.
Many inactivated greater than 99.9 per cent of virus after only 30 seconds of contact time and some inactivated 99.99 per cent of the virus after 30 seconds, they said.