CHAPEL HILL — Can mouthwash help limit someone's chances of spreading COVID-19 to others? UNC-Chapel Hill's Adams School of Dentistry is launching a clinical trial this month to find out.
So far, laboratory tests have shown commercially available mouthwashes can kill the virus that causes COVID-19. And although there is no clinical evidence that mouthwash can prevent the transmission of the virus, both the American Dental Association and the Centers for Disease Control and Prevention have recommended the use of mouthwashes before oral procedures.
UNC hopes its study can reveal that evidence, along with which types of mouthwashes are most effective.
"What we don't know is how well this works in practice," said Dr. Jennifer Webster-Cyriaque, a professor at UNC's dental school. "Doing this (study) will allow us to determine the efficacy."
If the trials are positive, mouthwash could become another "tool in the arsenal" for fighting COVID-19, Webster-Cyriaque said.
"We are becoming much more diligent as a society, but there are times in restaurant settings or other social settings where people may go without a mask," she said. "This might just help fill the gaps."
COVID-19 can easily spread when someone infected coughs, talks, sings or sneezes within close contact of someone. But if the viral load in their mouth is reduced, then it may be possible to reduce transmission.
However, COVID-19 also can spread from the nose.
"The mouth will not provide the complete picture, but (mouthwash) may get to the back of the throat, which is shared with the nose," Webster-Cyriaque said.
UNC hopes to enroll people in the trial that have tested positive for COVID-19 within seven days of participating. The school is still actively recruiting people.
The plan is to measure how much of the virus is in a participant's saliva before and after using mouthwash. Researchers would then collect and test their saliva every 15 minutes for up to an hour, measuring how long a reduction in their viral load or infectivity lasts.
The trial will include a variety of types of mouthwashes, including ones with antiseptic ingredients like cetylpyridinium chloride or ethanol, such as Listerine and Crest Pro-Health Mouthwash.