Severe Acute Respiratory Syndrome Coronavirus 2: A Protocol for Disinfection of Toothbrushes Free

To the Editor—In response to the article by Meister et al [1] on the Virucidal efficacy of different oral rinses against severe acute respiratory syndrome coronavirus disease 2 (SARS-CoV-2), this letter aims to contextualize how rinses and/or their active ingredients could reduce the cross-transmission capacity of SARS-CoV-2 by toothbrushes in familiar (individual use) and collective (school and hospital) environments, emphasizing the importance of toothbrush disinfection in the transmission of SARS-CoV-2 and suggesting a hygiene protocol.

Meister et al [1] found that several mouthwash formulations could reduce the viral load of SARS-CoV- 2 in saliva and its transmission. 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 [2]. Thus, disinfection of toothbrushes and hygiene of the oral cavity are important to control the transmission of SARS-CoV-2, especially in asymptomatic individuals or in those awaiting results of a test for coronavirus disease 2019 (COVID-19), because high viral loads are found in saliva, nasopharynx, and oropharynx [3].

However, it has not yet been established which rinse compositions would be most effective for controlling the transmission of SARS-CoV-2 [2]. Moosavi et al [4] reported the need for clinical trials to test the effectiveness of mouthwashes in reducing viral load but highlighted that the use of mouthwashes can reduce the risk of virus transmission. As clinical trials require time, the results of in vitro studies may provide us with valuable information on the effectiveness of mouthwashes against SARS-CoV-2 [1, 5]. There are still no data on the use of substances for the disinfection of toothbrushes against SARS-CoV-2. Thus, based on the results reported by Meister et al [1], 2 questions can be asked to suggest a brush disinfection protocol. First, did the rinses ensure the elimination of virus on the toothbrush? And second, is the immersion of the toothbrush in rinses effective in reducing the viral load of SARs-CoV-2?

Table 1 compares the different types of substances present in mouthwashes tested against SARS-CoV-2. According to the in vitro results, the antiseptic solution with the combination of ethanol and essential oils (Listerine Cool Mint) seemed to be the first choice among the solutions tested for disinfecting toothbrush bristles to control colonization and transmission of the virus [1, 6]. The indication would be to immerse the brush in this antiseptic solution for 20 minutes after brushing, in an individual container, and brushes must be stored dry, both individually and collectively [2]. Moreover, Meister et al [1] demonstrated that the time of mouthwash retention in the oral cavity, with the same substance, is 30 seconds to reduce viral load in the oral cavity. However, toothbrushes have retentive niches due to the presence of bristles and moisture; therefore, a longer exposure time should be recommended. Frazelle et al [7] recommend a 20-minute immersion time for brush disinfection. SARS-CoV-2 can remain infectious on inanimate surfaces for up to 9 days, and the disinfection of these surfaces with 0.1% sodium hypochlorite or ethanol between 62% and 71% significantly reduced its infectivity with 1-minute exposure [8]. Thus, at a collective level, such as in schools and hospitals, the toothbrush handles could be disinfected with 70% alcohol for 1 minute [8], after the hand-washing procedures.

Based on these studies, we suggest a hygiene protocol for disinfecting toothbrushes to reduce viral loads and the transmission of the SARS-CoV-2 virus in a family or collective environment: (1) hand washing with soap and water or rubbing with 70% alcohol gel; (2) disinfection of the toothbrush handle surface with 70% alcohol for 1 minute (only in a collective environment); (3) tooth brushing; (4) washing and new disinfection of the toothbrush handle with 70% alcohol for 1 minute (only in a collective environment); (5) immersion of the toothbrush in a solution of essential oils and ethanol (Listerine Cool Mint or similar formulation) for 20 minutes; (6) dry brush individual storage; and (7) in cases positive for COVID-19, discarding of the toothbrush.

As most studies of oral rinses against SARS-CoV-2 have been conducted in vitro, randomized clinical trials are needed to verify oral rinse effectiveness in preventing the spread of the virus, including evaluation of toothbrush disinfection. However, it is important to highlight the fact that Meister et al [1] showed the potential of an ethanol and essential oils combination to inhibit both different and mixed SARS-CoV-2 isolates. This makes it possible to apply the suggested protocol for disinfecting toothbrushes ,with the aim of preventing virus transmission in individual and collective contexts.

Note

Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

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