Sir, the established modes of SARS-CoV-2 transmission may be an incomplete picture. In their most recent scientific brief, the World Health Organisation acknowledge the evidence to support contact and respiratory droplet transmission of SARS-CoV-2. Accordingly, much of the government's infection prevention and control guidance for COVID-19 is centred around minimising transmission via these methods. The coronaviruses implicated in the previous SARS and MERS outbreaks caused enteric manifestations in conjunction with the respiratory symptoms experienced by many with COVID-19. Since the early retrospective cohort studies of patients in Wuhan, more recent observational studies report common gastrointestinal symptoms to be more prevalent than previously thought.1

SARS-CoV and MERS-CoV RNA were frequently detected in stool specimens of infected individuals. The New England Journal of Medicine case report of the first COVID-19 patient in the USA detected high SARS-CoV-2 viral load in their stool sample.2 Experts recognise the hypothesised faecal-oral route to be a plausible mode of transmission.

This route can facilitate transmission via fomites in the surrounding environment, in much the same way as indirect respiratory droplet transmission. Where toothbrushes are placed in close proximity to a toilet, there may be a heightened risk of harbouring SARS-CoV-2 from infected individuals. That families often house toothbrushes together, the risk of infecting other individuals could be made easier.

Rightly, the dental profession have reason to fear the aerosol generation from dental handpieces, particularly when the inverse-square law is applied to project the extent of dispersal. In a mechanistically similar way, toilet plumes may pose a similar challenge. Professor Addy offered reason to reinforce the role of toothbrushing with toothpaste, given the antimicrobial properties of toothpaste ingredients.3 Awareness and advice to limit toothbrush contamination might prove beneficial. Though the evidence base is yet to be established, no harm exists in recommending this as a precautionary measure in the preventive approach to COVID-19.