Sabrine Teixeira Grunewald, MD, MSc
January 14, 2021
SARS-CoV-2 can be transmitted, even from asymptomatic individuals, in different ways, including droplets, aerosols and, to a lesser degree, fomites.
Now, Brazilian researchers have evaluated the use of these products in a toothbrush disinfection protocol, they report in an article published online in The Journal of Infectious Diseases.
As highlighted by the authors in the text, published as a Letter to the Editor, individuals infected with SARS-CoV-2 have "high viral loads in saliva, nasopharynx and oropharynx," which can occur even in asymptomatic people.
Considering that toothbrushes can act as reservoirs for microorganisms and favor the transmission of diseases such as COVID-19, the authors estimate that disinfecting the brushes would be important to control the transmission of the virus in shared spaces.
A recent study demonstrated that commercially available mouthwashes can inactivate SARS-CoV-2 in vitro. The results showed that antiseptic solutions containing ethanol and essential oils — exemplified by the brand Listerine Cool Mint, to name one — had satisfactory effects in reducing viral load.
However, there are still no specific studies evaluating the effectiveness of different mouthwash solutions in the disinfection of toothbrushes, nor randomized trials showing that the use of such solutions would, in clinical practice, have a protective role against the transmission of COVID-19.
As proposed by the authors after a review of the available data on the subject, the disinfection of toothbrushes should follow the following steps:
- Wash your hands with soap and water or sanitize them with 70% alcohol
- Disinfect the toothbrush handle surface with 70% alcohol for 1 minute
- Brush your teeth
- Wash the brush and perform a new disinfection of its handle surface with 70% alcohol for 1 minute
- Leave the brushhead immersed in a solution with ethanol and essential oils for 20 minutes
- Store the brush individually after letting it dry
According to the authors, the steps for disinfecting the toothbrush with 70% alcohol are important when brushing in collective environments, such as in schools or in the workplace, and don't need to be performed in the household environment, if not desired.
Another important observation made by the authors: brushes used by individuals known to be positive for SARS-CoV-2 should be discarded immediately after use. The in vitro studies reviewed for the elaboration of the protocol showed it was possible to observe a satisfactory reduction in viral load with only 30 seconds of exposure to the tested solution. However, it is important to consider that the toothbrush has retentive niches of microorganisms because of its design -- hence the recommendation for immersion for a longer time.
More Studies Needed
"Toothbrushes play an essential role in oral hygiene, but they can also act as reservoirs for microorganisms, favoring the transmission of diseases in healthy and sick individuals," the authors write.
Although the in vitro efficacy of the ethanol and essential oils solution -- as well as that of alternative solutions such as povidone-iodine -- has been demonstrated in more than one study, more research is still needed.
"[R]andomized clinical trials are needed to verify oral rinse effectiveness in preventing the spread of the virus, including evaluation of toothbrush disinfection," conclude the authors.
The authors have disclosed no relevant financial relationships.