June 3, 2020
by John Hardie, BDS, MSc, PhD, FRCDC
From its earliest days COVID – 19 has been an evolving dilemma. As this is being written in mid May 2020, it would be foolish to predict the future profile of the infection. Instead, some of the known and unknown aspects of the disease will be discussed.
The presumptive pandemic – inducing virus known as SARS-CoV-2 was initially identified in 3 adults with severe pneumonia admitted in late 2019 to a hospital in Wuhan, Hubei Province in China. Coronaviruses are widely distributed in humans and are frequently associated with common cold – like symptoms. The Wuhan virus belonged to the coronavirus family but its unique, previously unknown genome sequencing resulted in it being referred to as a “novel” coronavirus. The discoverers of the virus did not believe that it satisfied the modern version of Koch’s Postulates, and in early 2020 other investigators noted that there was insufficient data to establish a causal relationship between this new virus and the respiratory diseases exhibited by the Wuhan patients. Despite these reservations, SARS-CoV-2 has become overwhelmingly accepted as a human pathogen responsible for a respiratory type illness.
Respiratory tract illnesses (RTI) are a major cause of morbidity and mortality, especially among the medically compromised. Corona viruses are responsible for 25% of seasonal RTIs. No matter the sensitivity of the tests used or how comprehensive the clinical investigations, in 15% of RTIs a causative agent (viral or non – viral) cannot be found. As far back as 2004 it was accepted that unknown pathogens are the cause of some RTIs. With this understanding it is entirely possible that the “new” coronavirus is one of the unknown pathogens that have been causing RTIs of unknown etiology for years. Since this coronavirus is related to the ones responsible for RTIs, and all are associated with similar signs and symptoms, it is a reasonable assumption that its pathogenicity will be similar to that of its cousins. If this idea has a modicum of credibility it should have tempered and influenced all official responses to the virus. This concept is supported by a recent study which concluded that from a statistical perspective SARS-CoV-2 is no more dangerous or deadly than other coronaviruses.
COVID-19 is the infection related to SARS-CoV-2. At present, its identification relies on sophisticated complex laboratory procedures involving reverse transcriptase polymerase chain reactions (RT-PCR). These are prone to errors in sampling, handling, technical procedures and interpretation. There is no “gold” standard against which the accuracy of the tests can be assessed. A 25th March report from the University of Oxford concluded that there was no reliable information on which to assess the false positive and false negative rates for the various RT-PCR tests used to identify COVID-19. It ought to be a concern that predictions and computer modelling are being performed using tests whose results have not been verified as to their accuracy. In fact models predicting the clinical progression of COVID-19, the length of hospitals stays and mortality risks are of questionable value.
Prepositions have the power to alter the number of COVID-19 related deaths. A patient dying with the coronavirus is in a different category than a patient dying from the coronavirus. The former represents an opportunistic infection of a compromised host, while the latter is the primary cause of death. (Many elderly men will die with prostate cancer, but not from it.) Much has been made of the seemingly high death rate in Italy. However, recently Professor Ricciardi, the country’s scientific adviser, corrected a previous misunderstanding by stating that, “On re-evaluation by the National Institute of Health, only 12% of death certificates have shown a direct causality from coronavirus, while 88% of patients who have died have at least one morbidity many had two or three.” Phrases such as “related to COVID-19” or “COVID-19 is assumed to have caused death” do not infer that the infection was the primary cause of death. The recording of deaths during this pandemic will remain confusing and imprecise until there is a clearly defined and internationally accepted definition of what constitutes a death “primarily from COVID-19.”
The Case Fatality Rate (CFR) is the number of deaths divided by the number of known infections. This varies widely and depends on the demographics and numbers of those being screened. During the early phases of a pandemic, when mild and/or asymptomatic cases are not screened, the CFR will provide a skewed overestimate of the number of deaths – inevitably leading to a media feeding frenzy of fear mongering and dire predictions. A more accurate assessment of death rates is the Infection Fatality Rate (IFR). This is the number of deaths divided by the true number of infections (diagnosed and those asymptomatic) in the study population. This depends on knowing the prevalence of the infection in the community. IFRs depend on screening at random large swaths of the population. Inevitably, they will produce lower death rates compared to the case fatality rates. Once established, IFRs are a useful means of comparing the success of the preventive approaches adopted by different countries. They will also be useful in determining to what degree deaths from COVID-19 have differed from those associated with seasonal influenza.
The widespread use of Personal Protective Equipment (PPE) and the adoption of social distancing have not been advocated for previous influenza – type pandemics. Traditionally, quarantine has been recommended for the sick, not for the healthy who might become infected. The evidence in support of PPE and social distancing is weak and mainly based on simulations studies. Investigations have reported no advantage of N95 masks over regular surgical masks in the prevention of flu type infections among clinical staff. Irrespective of whether or not masks are worn, the same air is shared by all. Social distancing does not alter that fact and, while it will not prevent exposure to the virus, the degree to which it reduces the spread of the virus remains unknown. It is entirely possible that social distancing could simultaneously reduce the height but lengthen the span of the “curve”.
The use of PPEs by health care workers creates an intimidating physical barrier between them and their patients. The friendly reassuring smile and warm handshake so beneficial to those in physical or emotional distress is replaced by a human robot encased in latex and plastic. It is feared that this loss “of the milk of human kindness” will have a deleterious effect on caring professions and the patients they serve.
There is increasing evidence that the overwhelming majority of those infected with COVID-19 will recover from it. Even those vulnerable to contract the infection have a reasonable chance of recovery. It is highly likely that, as more is known about the Infection Fatality Rate of COVID-19, its pathogenicity will be considerably less than originally predicted, and might well equal that of a severe influenza. This should permit a lessening of the fear, hysteria and suspicion which have characterized COVID-19.
Writing in the British Dental Journal in 1996 Fallowfield said, “It is imperative that when notes for guidance become requirements they are based upon scientific fact rather than someone’s subjective interpretation of current best practice.” In 1981 JD Miller, an early supporter of Infection Control, emphasized that, “We must be extremely careful in public health to minimize the actions we take based on no or few facts.” His colleague TC Eickhoff expressed his concern that, “…we rarely determine that the recommendations we make, in fact, do what we want them to do within a cost effectiveness figure that we can accept.”
Accordingly, dentistry would be well advised to thoroughly review all that is known about COVID-19. It is not an exaggeration to state that a surfeit of non-peer reviewed articles on COVID-19 are being rushed to publication on a weekly basis. Many rely on non-validated RT-PCR testing to determine the presence of the virus. A recent study suggesting the transmission from contaminated surfaces and equipment did not assess the viability of recovered viruses, used inconsistent methods and a small sample size. Another investigation promoting the airborne transmission of the virus used highly controlled laboratory conditions which did not simulate clinical settings. The World Health Organizations has warned that, “…the detection of RNA in environmental samples based on PCR-based assays is not indicative of viable virus that could be transmissible.” Armed with this information, a comprehensive analysis ought to be performed to determine if additional infection control protocols are clinically justified and economically viable. Failure to so do would be an abrogation of the responsibility that the profession has to its practitioners and patients.
It is entirely possible that pre-treatment hydrogen peroxide oral rinses, the use of rubber dam and high velocity suction will do much to reduce airborne transmission of SARS-CoV-2 from dental aerosols.
The unknowns and uncertainties surrounding COVID-19 have driven public health and government responses to COVID-19. Perhaps, faced with an apparent new disease, such reactions were inevitable. Fortunately, accumulating new data suggests that the novel coronavirus is less dangerous than thought. This permits the author’s ban on predictions to be rescinded. The peculiar reality of COVID-19 is that its forecasted dire outcomes will not occur but that SARS-CoV-2 will mutate (if it has not already done so) to establish a symbiotic relationship with its human host for many generations to come.
(References pertinent to the above article are available on request)
About the Author
John Hardie, BDS, MSc, PhD, FRCDC – Although retired from practice Dr. Hardie maintains a thirty plus years interest in the discipline of infection control as it relates to dentistry. He has published extensively on the subject and has lectured on it and related subjects throughout North America and in the UK, Europe, the Middle and Far East.
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