Mouthwashes, oral rinses may inactivate human coronaviruses, study finds
Penn State
The results indicate that some of these products might be useful for reducing
the viral load, or amount of virus, in the mouth after infection and may help
to reduce the spread of SARS-CoV-2, the coronavirus that causes COVID-19.
Craig
Meyers, distinguished professor of microbiology and immunology and obstetrics
and gynecology, led a group of physicians and scientists who 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% solution of baby shampoo, a neti pot,
peroxide sore-mouth cleansers, and mouthwashes.
The
researchers found that several of the nasal and oral rinses had a strong
ability to neutralize 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," Meyers said. "The products we tested are readily available
and often already part of people's daily routines."
Meyers and colleagues 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. 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 envelopes of
the human coronavirus tested and SARS-CoV-2 are genetically similar so the research
team hypothesizes 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 results
were published in the Journal of Medical Virology.
The 1% baby shampoo solution, which is often used by head and neck doctors to rinse the sinuses, inactivated greater than 99.9% of human coronavirus after a two-minute contact time. Several of the mouthwash and gargle products also were effective at inactivating the infectious virus.
Many inactivated greater than
99.9% of virus after only 30 seconds of contact time and some inactivated
99.99% of the virus after 30 seconds.
According to Meyers, the results with mouthwashes are promising and add to the findings of a study showing that certain types of oral rinses could inactivate SARS-CoV-2 in similar experimental conditions.
In addition to evaluating the
solutions at longer contact times, they studied over-the-counter products and
nasal rinses that were not evaluated in the other study. Meyers said the next
step to expand upon these results is to design and conduct clinical trials that
evaluate whether products like mouthwashes can effectively reduce viral load in
COVID-19-positive patients.
"People who test positive for COVID-19 and return home to quarantine may possibly transmit the virus to those they live with," said Meyers, a researcher at Penn State Cancer Institute.
"Certain professions including dentists and
other health care workers are at a constant risk of exposure. Clinical trials
are needed to determine if these products can reduce the amount of virus
COVID-positive patients or those with high-risk occupations may spread while
talking, coughing or sneezing. Even if the use of these solutions could reduce
transmission by 50%, it would have a major impact."
Future
studies may include a continued investigation of products that inactive human
coronaviruses and what specific ingredients in the solutions tested inactivate
the virus.
Janice
Milici, Samina Alam, David Quillen, David Goldenberg and Rena Kass of Penn
State College of Medicine and Richard Robison of Brigham Young University also
contributed to this research.
The
research was supported by funds from Penn State Huck Institutes for the Life
Sciences. The researchers declare no conflict of interest.