Certain oral antiseptics and mouthwashes may be able to inactivate human coronavirus, according to a research study conducted by Penn State College of Medicine. The results suggest that some of these products may be useful to reduce the viral load or amount of virus in the mouth after infection and to contain the spread of SARS-CoV-2, the corona virus that causes COVID-19.
Craig Meyers, a distinguished professor of microbiology and immunology as well as obstetrics and gynecology, led a group of physicians and scientists who tested several mouth and nasopharyngeal lavages in a laboratory environment for their ability to inactivate human corona viruses that are similar in structure to SARS-CoV-2. Among the products evaluated are a 1% solution of a baby shampoo, a Neti pot, peroxide mouthwashes for sore spots and mouthwashes.
The researchers found that several of the nasal and mouth rinses had a strong ability to neutralize human corona virus, suggesting that these products may have the potential to reduce the amount of virus spread by people who are COVID-19 positive.
“While we are waiting for a vaccine to be developed, methods to reduce transmission are needed,” said Meyers. “The products we have tested are readily available and often already part of people’s daily routine.
Meyers and colleagues used a test to replicate the interaction of the virus in the nasal and oral cavity with the rinses and mouthwashes. The nasal and oral cavity are important entry and transmission points for human corona viruses. They treated solutions containing a strain of the human corona virus, which served as an easily available and genetically similar alternative to SARS-CoV-2, with the baby shampoo solutions, various antiseptic peroxide rinses and various mouthwashes. They 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 shells of the tested human corona virus and SARS-CoV-2 are genetically similar, so the research team hypothesized that a similar amount of SARS-CoV-2 could be inactivated when exposed to the solution.
To measure how much virus was inactivated, the researchers brought the diluted solutions into contact with cultured human cells. They counted how many cells were still alive after a few days of exposure to the virus solution and used this figure to calculate the amount of human corona virus that was inactivated as a result of exposure to the tested mouthwash or mouthwash. The results were published in the Journal of Medical Virology.
The 1% baby shampoo solution commonly used by head and neck surgeons to rinse the sinuses inactivated more than 99.9% of human coronavirus after a two-minute contact time. Several of the mouthwash and gargle products were also effective in inactivating the infectious virus. Many inactivated more than 99.9% of the virus after only 30 seconds contact time and some inactivated 99.99% of the virus after 30 seconds.
According to Meyers, the results with mouthwashes are promising and complement the results of a study showing that certain types of mouthwashes could inactivate SARS-CoV-2 under similar experimental conditions. In addition to evaluating the solutions at longer contact times, they investigated over-the-counter products and nasal rinses that were not evaluated in the other study. Meyers said the next step to expand on these results was to plan and conduct clinical trials to determine whether products such as mouthwashes could effectively reduce viral load in COVID-19 positive patients.
“People who test positive for COVID-19 and return home in quarantine may be able to transmit the virus to those they live with,” said Meyers, a researcher at the Penn State Cancer Institute. “Certain professions, including dentists and other healthcare workers, are at constant risk of exposure. Clinical studies are needed to determine whether these products can reduce the amount of the virus in COVID-positive patients or whether people in high-risk professions can spread while speaking, coughing or sneezing. Even if the use of these solutions could reduce transmission by 50%, the impact would be significant.
Future studies could include further investigation of products containing inactive human corona viruses and what specific ingredients are needed to reduce the risk of transmission.