Abstract
The first of a continuing series of articles to keep the readers abreast of the current data on COVID-19 pandemic impacting dentistry
COVID-19 and dentistry: perspectives of an unfolding pandemic
From Volume 47, Issue 6, June 2020 | Pages 531-532
Article
The dental health profession faces a daunting new challenge with the emergence of a novel viral disease, Coronavirus Disease-19 (COVID-19), a form of atypical pneumonia caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which may also cause multi-system infections. At the time of writing, this highly infectious disease, now an unprecedented, worldwide pandemic, has spread to more than 150 countries, infecting 5.7 million, with over 355,00 deaths. A significant proportion of those affected are unsuspecting healthcare workers, including dentists. The major transmission mode of SARS-CoV2 appears to be through droplet/aerosol spread and related subsidiary modes, such as close contact via virus-infested fomites.
The rapidly evolving pandemic is highly likely to have an enormous impact on the routine practice of dentistry, as well as the behaviour of their close support personnel, not only in terms of the related morbidity and mortality, but also the associated financial outlays entailing practice management. Additionally, the dental community has to be constantly vigilant in the face of new facts and figures that are incessantly emerging. COVID-19 Commentary is an attempt at providing the reader with current perspectives of the research findings that impact the profession. Here are discussed in brief, the different coronavirus infections, their possible origins, and why new viral diseases such as COVID-19 emerge.
More than a decade ago, in a retrospective review on the Severe Acute Respiratory Syndrome (SARS), when the epicentre of infection was China and Hong Kong, we opined that ‘… the dental community cannot let down its guard, and must be constantly aware of impending infectious threats in various guises, as well as recrudescence of disease, that may challenge the current infection control regimen.’1 Unfortunately, with the pandemic of COVID-19, this ominous statement has proven to be true, as the coronavirus, which belongs to the same family of viruses causing the common cold, has mutated into a newer, more infectious and a deadly form in the guise of SARS-CoV-2 (Figure 1).
Coronavirus infections
New virus infections arise unceasingly, always a few steps ahead of the combative armamentarium which we humans are unleashing upon them at the slightest hint of their emergence. Such new infections that have emerged during the last few decades include, Ebola, Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) and Middle East Respiratory Syndrome coronavirus (MERS-CoV) infections, H1N1 infection, Zika Virus infection, and now COVID-19.
According to an analysis by the O*Net Bureau of Labor Statistics of the USA, dentists are the professional group running the highest risk of contracting an airborne disease such as the COVID-19.2 Indeed, the dental community is confronted with this risk not only during the pandemic period, but also once its critical acute phase wanes, into the foreseeable future. Alarmingly, there appears to be healthy asymptomatic carriers of the SARS-CoV-2 in the community, and they may pose a constant threat until the disease disappears. Various reports indicate the community asymptomatic carrier state ranging from 20% to, as high as 80%.3 One silver lining in this dark cloud is the fact that other coronavirus diseases, such as SARS and MERS, disappeared spontaneously after the epidemic, and it is feasible that COVID-19 may also naturally regress over a period of time, due to waning viral infectivity on repeated passage amongst humans.
Coronaviruses and their origins
Coronaviruses are enveloped RNA viruses distributed mainly among mammals and birds, and cause respiratory, enteric, hepatic and neurologic diseases. Six coronavirus species are known to cause human disease.4 Four of them typically cause common cold symptoms in healthy individuals, while SARS-CoV and MERS-CoV sometimes cause fatal illnesses (Table 1).
| Year of Discovery | Proper Name | Synonym/s | Disease |
|---|---|---|---|
| Unknown | Human coronavirus 229E | Alphacoronavirus | Human common cold |
| Unknown | Human coronavirus OC43 | Betacoronavirus | Human common cold, infects cattle |
| 2003 | SARS coronavirus | SARS-CoV1 or ‘SARS-classic’ | Human respiratory tract infections |
| 2004 | Human coronavirus NL63 | HCoV-NL63, New--Haven coronavirus | Human respiratory tract infections |
| 2005 | HKU1 | Betacoronavirus | Human respiratory tract infections |
| 2012 | MERS-CoV | Novel coronavirus 2012 and HCoV-EMC | Human respiratory tract infections |
| 2019 | SARS-CoV2 | COVID-19 virus (previously; 2019-CoV or ‘novel coronavirus 2019’) | Human COVID-19 -respiratory tract (mainly) and multi system infections |
For a new strain of virus, such as SARS-CoV-2, to emerge, two divergent viruses must simultaneously infect an intermediate host, whence the host acts as a ‘blender’, as it were, of the two different strains to create a brand new strain. In the context of COVID-19, the current genomic comparisons suggest that it is a recombinant viral product between a bat virus and another anonymous virus, in a small Pangolin species. Nevertheless, this hypothesis of the origin of SARS-CoV-2 remains to be verified.
Reasons for emergence of new viral diseases
What are the reasons for the incessant emergence of these diseases at almost a constant pace over the millennia? Almost two decades ago, an eminent committee of the Institute of Medicine (IOM) in USA performed a comprehensive evaluation of why new diseases emerge and old diseases re-emerge.5 In their subsequent seminal report, they concluded the following key reasons as the most likely for new infections:
The IOM report was impactful in highlighting, for the first time, the critical importance of keeping an eye on emerging infectious diseases. Indeed, this phenomenon itself has been described since ancient times, and the currently applied concepts of quarantine and social distancing, to prevent further spread of the disease, has also been in existence from such times. To some extent, the containment of the viral diseases in historic times could be attributed to the virtual non-existence of transcontinental travel then. Hence it is not surprising that pandemics arise in the contemporaneous, highly connected world today, where air travel could transport people and infections from one continent to another within 24 hours. This, combined with the high infectivity of SARS-CoV-2, appear to be the major reasons for the current pandemic. The latter qualities of the virus, and its stubborn persistence, inform the infection control practices in dentistry, as well the clinical routine of our profession. Hence, the focus of the next article will be SARS-CoV-2 spread, its infectivity and survival in air, and on animate and inanimate surfaces – a topic that is very close to the heart of dental practice.