Article by Dr Tim Sandle
COVID-19 is continuing to have a global impact, with infection numbers rising daily. It is caused by the virus SARS-CoV-2, (Severe Acute Respiratory Syndrome coronavirus 2) and occurs due to close contact with an infected person, by exposure to coughing, sneezing, breathing in droplets, or airborne particles, or from touching contaminated surfaces [Jayaweera, 2020].
If viral particles are aerosolised during care, they can potentially travel from an infected person and lead to viral contamination elsewhere in the environment (a distance of up to ten metres indoors) [Morawska and Cao, 2020]. The SARS-CoV-2 virus can be viable in suspended aerosols for up to three hours [van Doremelan, 2020].
Recent studies show that virus shedding from the upper respiratory tract is extremely high in the early stages of the disease [Chin 2020]. It is therefore recommended that the role of saliva and the salivary glands as a source of SARS-CoV-2 should be considered a risk factor even in asymptomatic carriers [Moosavi, 2020]. This is particularly relevant in hospitals, where cases of COVID-19 are increasing on a daily basis.
Public Health England has recently drawn attention to the importance of mouth care and oral hygiene. Their new guidance relates to hospitalised adults and children with COVID-19 or suspected COVID-19 and advises that:
‘Supporting seriously ill patients’ mouthcare is an important part of overall patient care. If oral hygiene is neglected, the mouth rapidly becomes dry and sore. The aim of good mouthcare for patients in hospital is to maintain oral cleanliness, prevent additional infection and reduce the likelihood of developing bacterial pneumonia. On admission include the mouth in the patient’s assessment and care plan’ [PHE, 2020].
Although, there is incomplete information about how SARS- CoV-2 moves from the throat and nose to the lungs, viral shedding is likely to be a significant factor meaning that oral rinses could represent a potential method of inactivating and removing infective particles generated in the throat [O’ Donnell, 2020]. They could also help fulfil the PHE guidance on COVID-19 mouth care.
This article examines the role played by the throat and salivary glands in transmitting infection and what benefits could be offered by mouth rinses in the care of confirmed and suspected COVID-19 patients.
New studies show that virus shedding from the upper respiratory tract is extremely high in the early stages of COVID-19 [Chin 2020]. The viral load found in saliva is not only consistently high but also higher than that from the oropharynx, meaning that saliva is likely to be capable of SARS‐CoV‐2 transmission [Chitguppi, 2020].
The throat and sputum are abundant in viral particles, which peak 5–6 days after the onset of symptoms, then decline thereafter. Many asymptomatic patients have modest levels of detectable viral RNA in their oropharynx for at least 5 days, which is similar to individuals with clinical symptoms [O’ Donnell, 2020]. Studies have shown that coronavirus can be transmitted to others by asymptomatic carriers. This may be due to the incubation period ranging from 0 to 24 days and also to some asymptomatic people being unaware they are carrying the virus [Moosavi, 2020].
Viral load correlates with older age and a study of 76 patients in Nanchang, China, showed that those with severe SARS-CoV-2 tend to have a higher viral load and a longer virus-shedding period than those with mild disease. Similarly, viral load was linked with lung disease severity in a study of 12 patients with pneumonia.
Unsurprisingly, this means that the potential for transmission is high early on in the disease process. While further studies are needed to better understand the relationship between viral load and symptom severity, it is expected that higher levels of viral shedding in the throat or lungs might be associated with an increased ability to infect others. [O’Donnell, 2020]
Coronaviruses, in common with many viruses like influenza are surrounded by a fatty layer, called a ‘lipid envelope.’ This ‘envelope’ is highly sensitive to agents that disrupt the lipid membrane. Until recently there had been little discussion about the potential role of oral rinsing in preventing transmission.
Although there is much evidence to suggest that a mouth rinse significantly reduces the bacterial count in aerosols [Harrell, 2004], viral efficacy has received little attention. But a recent study has examined the virucidal efficacy of a number of mouth rinses against SARS-CoV-2. The study was undertaken under laboratory conditions, designed to simulate real-life events of virus containing nasopharyngeal secretions. The researchers found that several mouth wash formulations, including one containing octenidine, showed significant SARS-CoV-2 inactivating properties under these test conditions [Meister TL, 2020]. They concluded ‘that oral rinsing might reduce the viral load of saliva and could thus lower the transmission of SARS-CoV-2.’
Oral rinsing with a suitable mouth wash could be adopted in hospitals as an additional precaution against the transmission of the COVID-19 virus. Particularly as they have the potential to reduce the viral load in a patient who could be an asymptomatic or pre-symptomatic carrier [Chitguppi, 2020].
Octenidine has been used in wound care and body washing in hospitals for many years. Its key properties include a broad antimicrobial spectrum [Chow, 2018], good skin and mucous membrane compatibility [Gastmeier, 2016], a residual long term action [Brill, 2015] and no known resistance (in contrast, bacterial resistance to chlorhexidine is between 5-10%) [Spencer, 2013].
A mouth rinse may not offer sufficient protection if it reduces the viral load only when it comes in contact with the virus in the mouth, without being able to maintain a low viral load after it is expectorated. Therefore, a mouth rinse with persistent activity to maintain low viral loads in the mouth for a period of time is advantageous [Chitguppi, 2020].
Along with the use of face masks, social distancing, eyewear and environmental cleaning and disinfection, an additional recommendation for the use of antiviral mouth rinses with a long residual effect can significantly help in the prevention of SARS-COV-2 infection in hospitalised patients, as well as fulfilling PHE requirements for effective mouth care.
Brill F et al. Residual antiseptic efficacy of octenidine dihydrochloride versus chlorhexidine gluconate in alcoholic solutions, Antimicrobial Resistance and Infection Control 2015, 4 (Suppl 1):P33
Chin BS, et al. Clinical course and outcomes of patients with severe acute respiratory syndrome coronavirus 2 infection: a preliminary report of the first 28 patients from the Korean cohort study on COVID-19. J Korean Med Sci. 2020;35(13): e142.
Chitguppi R, Mouth rinses with substantivity can prevent COVID-19 spread and protect the healthcare workers, https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3638601 accessed 21st September 2020
Chow A et al. Intranasal octenidine and universal antiseptic bathing reduce methicillin-resistant Staphylococcus aureus (MRSA) prevalence in extended care facilities. Epidemiology and Infection, 2018, 146, 2036–2041.
van Doremalen N et al, Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1, N Engl J Med, 2020 doi:10.1056/NEJMc2004973
Gastmeier P et al. An observational study of the universal use of octenidine to decrease nosocomial bloodstream infections and MDR organisms, J Antimicrob Chemother 2016; 71: 2569–2576
Harrel SK and Molinari J (2004) Aerosols and splatter in dentistry: A brief review of the literature and infection control implications. J Am Dent Assoc 135: 429–37
Jayaweera M et al. “Transmission of COVID-19 virus by droplets and aerosols: A critical review on the unresolved dichotomy.” Environmental research vol. 188 (2020): 109819. doi:10.1016/j.envres.2020.109819
Meister TL et al. Virucidal Efficacy of Different Oral Rinses Against Severe Acute Respiratory Syndrome Coronavirus 2, Journal of Infectious Diseases, 2020.
Morawska L. and Cao J. Airborne transmission of SARS-CoV-2: The world should face the reality. Environ. Int. 2020;139:105730.
Moosavi MS et al. Antiviral mouthwashes: possible benefit for COVID-19 with evidence-based approach, Journal of Oral Microbiology, 2020, 12:1, 1794363
O’Donnell VB et al, Potential Role of Oral Rinses Targeting the Viral Lipid Envelope in SARS-CoV-2 Infection FUNCTION, 2020, 1(1): zqaa002
Public Health England, Mouthcare for patients with COVID-19 or suspected COVID-19, 2020
Spencer C et al. Daily bathing with octenidine on an intensive care unit is associated with a lower carriage rate of methicillin-resistant Staphylococcus aureus, Journal of Hospital Infection 83 (2013) 156-159.