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Coronavirus Disease 2019
Understanding COVID-19: A Primer
Pathologist Waldemar Schmidt answers basic biology questions.
Posted May 5, 2020 Reviewed by Abigail Fagan
As a psychologist, I am not well-versed in the technical language of viruses. As such, I took some time to ask my friend, Dr. Waldemar Schmidt, who is an MD/Ph.D. pathologist some questions about the virus.
1. What is the size of the coronavirus?
Robert Eliot’s aphorism applies to our current pandemic: Rule No. 1: Don't sweat the small stuff. Of course, he also asserted: Rule No. 2: It's all small stuff, and that is true here also. The actual coronavirus is very small stuff relative to the everyday world of the human, averaging about 120 nm (1 nanometer = 1 / 25,400,000th of an inch) in diameter. Of course, everything is relative, and the virus is actually quite large in relationship to some other viruses. And, of course, it has a very large effect on the world.
2. What, exactly, is a virus, and why do we call this a corona virus?
In biology, a virus refers to a “submicroscopic, non-cellular structure consisting of a core of DNA or RNA surrounded by a protein coat, that requires a living host cell to replicate, and often causes disease in the host organism" (see here).
It is named a corona virus based on its morphology and shape. It is part of the family Coronoviridae, which are technically designated as “enveloped, positive-sense, single stranded RNA viruses.” These viruses are crowned by a collection of protruding molecules, which appear similar to the solar corona. To place viruses on the Tree of Knowledge System, they lie in that "in-between" space that exists between the dimensions of Matter and Life. By this I mean they behave similarly to both large molecules and full-fledged cells, and yet they also behave significantly different than both. Viruses are molecules that have very primitive and limited metabolic capacities and cannot themselves metabolize energy on their own accord, like cells can. They are capable of replicating under the appropriate conditions — but they cannot do so on their own. To replicate, they must take over a cell’s machinery.
3. What is the difference between corona virus, nCoV-2, and COVID-19?
There is important information to unpack with this question. The term corona virus simply means that the virus referenced is a member of the family Coronoviridae. The corona virus with which we currently are struggling is named nCoV-2 (aka SARS-CoV-2). The common name (nCoV-2) designates the virus as novel, Co refers to its Coronoviridae membership, V = Virus, and 2 denotes it as a second cause of SARS (Severe Acute Respiratory Syndrome) (see here).
nCoV-2 is designated as novel because it was not previously identified. That is not to imply that we haven’t encountered Coronaviridae before. In fact, there are varieties of corona virus with which both animals and humans have been acquainted for eons. In humans, corona viruses are known to cause about 15% of common colds – most being caused by rhinoviruses. Two other corona viruses are associated with SARS: those which caused the first corona virus-caused SARS (SARS-CoV) and MERS (Middle East Respiratory Virus; MERS-CoV). The current pandemic is caused by nCoV-2.
The disease it causes is called COVID-19, the first cases of which were identified in 2019 – hence CoronaVirusInfectiousDisease-19. The primary source of nCoV-2 is not firmly established but evidence favors a zoonotic origin.
4. What exactly is the COVID—19 illness that people contract?
At this point a caveat is warranted: when describing or reading about COVID-19, large amounts of both humility and skepticism are warranted. For students of human disease, this is a particularly remarkable and historic event — as far as we know, we humans have never previously been exposed to nCoV-2 or have suffered from COVID-19. As a result, we are learning new features of both the pathogen and the disease every day.
Initially, COVID-19 was considered a highly infectious pneumonic illness that could progress to SARS. Over time, we learned that nCoV-2 induces a wide array of clinical signs and symptoms. At one end, there are patients who harbor the virus, but do not have symptoms and possibly never would develop them. At the other end, we see people with severe pneumonic disease, who developed SARS and did not survive.
The virus is easily transmitted between humans, with one infected person infecting on average 2.2 others (R0=2.2). This situation is even more problematic since it appears that the infected, and possibly those harboring the virus, will shed the virus before they become symptomatic. Further, the initial symptoms associated with the disease are essentially identical with those of a cold, even in those who progress to more severe disease.
Where we initially saw COVID-19 as a respiratory tract pathogen capable of progressing to SARS, it is now apparent that multiple other organ systems can be involved (heart, liver, kidneys, hemostasis system) resulting in multiple organ dysfunction and failure (MOD & MOF), heart failure, arrhythmias, renal failure, cytokine storm, etc. At present, we do not know how or why this wide array of symptoms and variable clinical courses occurs.
5. How is COVID-19 diagnosed?
Initially, COVID-19 was considered a pneumonic disease, but we now recognize the disease’s initial manifestations were variable. We also know that the quintessential symptom triad (cough, fever, dyspnea) is indicative of the advanced disease, and that up to 80% of those in the early stages were asymptomatic. This is one of the reasons we need for diagnostic testing. Unfortunately, a reliable, widely accessible test remains unavailable. Many trials are underway to produce reliable tests both for infection and evidence of immunity.
Because the symptomatology is shared with influenza, testing is often first done to rule out influenza, although it does not rule in COVID-19. Currently, health care professionals are struggling to make early diagnoses and largely rely upon mitigation of symptoms to manage the disease. We await the availability of universally available, reliable, point-of-care testing to diagnose and manage COVID-19, as well as to monitor the population — especially since nCoV-2 is now everywhere on every continent and even on ships at sea. Hopefully, our ability to diagnose who has the illness, who is spreading the illness, and who has developed possible or likely immunity will emerge in the months ahead.
6. How is COVID-19 treated?
There is no medication available to specifically treat the disease. In the interim, supportive care is given in response to the patient’s condition and other specific medications and therapies are applied to control complications and comorbidities. The large number of trials searching for a specific treatment are encouraging. At present, the anti-viral remdesivir is promising. I am hopeful that early treatment using remdesivir could be effective, and that research is underway.
7. May we find relief through a vaccine — and when?
At this stage, the best guess is that nCoV-2 and COVID-19, in all of its manifestations, are destined to become a common and continual problem, similar to influenza. Populations respond effectively to such agents by developing herd immunity, which requires immunity in approximately 80% of the population or more. Immunity is achieved either by surviving COVID-19 or via vaccination. As nCoV-2 passes repeatedly through the world’s population, presumably some level of herd immunity will be achieved.
However immunity is accomplished, we should be aware that there are ongoing concerns about what this means. Whether nCoV-2 will produce a lasting immunity remains to be demonstrated — with a coronavirus that produces colds, immunity is not lasting, which is why you can get colds over and over. Immunity is long lasting for small pox. We do not know what immunity will look like with COVID-19.
Further, the development of a vaccine is a laborious and time-expensive process. First, since nCoV-2-induced disease can be fatal, a vaccine cannot be evaluated using direct challenge with the virus. Instead, some non-pathogenic part of the virus must employed to spark the body’s immune response. Presently, it remains to be determined which part of the virus might evoke such a response.
Secondly, a candidate vaccine must be proven safe — usually via trials in animals and then humans. Thirdly, we would then need to determine if a safe vaccine produces an effective immune response, and if so, we would need to determine how long the effective immunity lasts. Given these factors, it is no surprise, then, that 12-18 months to a vaccine is a conservative estimate.
8. What may be done until a treatment, cure, or vaccine is available?
Avoidance of exposure to the virus and good health practices, such as hydration, a healthy diet, exercise, good sleep practices, and maintaining a supportive daily routine are important. Given how infectious the disease is, we must acknowledge that the avoidance of exposure is hard. Facial covering and gloves are important, of course, as is social distancing, but the later impedes our basic social needs for connection and the capacity of our economic system to operate effectively.
Unfortunately, in terms of solutions, there are no easy answers. Perhaps the best we can do is try to not sweat the small stuff, recognize we are in an intense and difficult situation, engage in practices that foster resilience and connection, and try to engage in wise decision-making on the hoped-for path toward a brighter future.
