Could there be a link between oral hygiene and the severity of SARS-CoV-2 infections?

Abstract

On 30 January 2020, the World Health Organisation identified COVID-19, caused by the virus SARS-CoV-2, to be a global emergency. The risk factors already identified for developing complications from a COVID-19 infection are age, gender and comorbidities such as diabetes, hypertension, obesity and cardiovascular disease. These risk factors, however, do not account for the other 52% of deaths arising from COVID-19 in often seemingly healthy individuals. This paper investigates the potential link between SARS-CoV-2 and bacterial load, questioning whether bacteria may play a role in bacterial superinfections and complications such as pneumonia, acute respiratory distress syndrome and sepsis. The connection between COVID-19 complications and oral health and periodontal disease is also examined, as the comorbidities at highest risk of COVID-19 complications also cause imbalances in the oral microbiome and increase the risk of periodontal disease. We explore the connection between high bacterial load in the mouth and post-viral complications, and how improving oral health may reduce the risk of complications from COVID-19.

Fig. 1

The different outcomes of different treatment options for COVID-19 patients.Reproduced from Gautret P, Lagier J-C, Parola P et al., Hydroxychloroquine and azithromycin as a treatment of COVID-19: results of an open-label non-randomized clinical trial, Int J Antimicrob Agents, 2020, Elsevier

Fig. 2

Bacteria that colonise the mouth are shed into the saliva. The pathogenic bacteria within the saliva can then be aspirated into the lower respiratory tract and cause or aggravate an infection. Reproduced with permission from Scannapieco F A, Role of Oral Bacteria in Respiratory Infection, J Periodontol, 1999, John Wiley and Sons.