The outbreak of a new coronavirus has sent panic rippling across the world at speeds far faster than the actual virus travels. If this is somehow the first exposé you’ve encountered, “coronavirus” is the somewhat-misleading name now commonly used to refer to the 2019 novel coronavirus (or 2019-nCoV, for short), which emerged in Wuhan this December, and has, as of February 4, spread to at least 27 countries and caused over 20, 000 recorded infections, most of them in China.
The name is misleading because this coronavirus is only one member of the much larger coronavirus family, so-called for the spikes on the surface of the virus which make them look like microscopic suns (or crowns, depending on who you ask). These viruses are highly diverse in terms of the species they infect, and in their virulence (the amount of harm they cause to their hosts). Of the several coronavirus species adapted to infect humans, most cause mild respiratory illness—also known as the common cold. In fact, coronaviruses are responsible for about 40 percent of all cases of the common cold, which means that you’ve almost certainly been infected by a coronavirus in your lifetime. The majority of coronaviruses, though, are only capable of infecting animals (some infect birds, others infect non-human mammals, notably bats).
There are also rare cases where coronaviruses jump from their animal hosts to infect humans, in what is called zoonotic transmission. Sustained and productive infection of human hosts by an animal-adapted virus, though, requires the virus to mutate so it can attach to human cells. Two notable coronaviruses emerged into the human population this way in recent memory: SARS and MERS. SARS, or severe acute respiratory syndrome, originated in bats and was transferred to humans through civet cats, leading to a severe outbreak in 2002 and 2003. MERS (Middle East respiratory syndrome) emerged in 2012, transmitted from bats through camels to humans, and is still active in some parts of the Middle East.
And now,the 2019 novel coronavirus appears to have joined their ranks. “Novel” in this context means that this virus has not been previously characterized, and so, it is likely to have originated from an animal reservoir. Sequencing of the novel coronavirus has revealed close similarities to bat coronaviruses, suggesting that it, like SARS, also originated from bats, though we still don’t know how exactly the first human transmission event occurred. Importantly, moderate levels of human-to-human transmission have been reported.
One of the reasons why SARS and MERS have caused more severe illness in humans than the various coronaviruses responsible for the common cold is because both SARS and MERS originated from animal reservoirs. A successful virus must balance its ability to replicate within a host with its ability to transmit from host to host, activities which are often at odds with each other, because the more a virus replicates within a host, the more it harms the host. Many viruses do not actually benefit from killing their hosts quickly, or causing severe illness, because a host who is able to move around is one who can more effectively transmit the virus to others, although the virus also requires replication to produce enough particles for productive transmission. A virus finds this balance between within-host replication and host-to-host transmission through co-evolution with its host. This is why, when a virus leaps to a new host, the infection is often so severe. The novel coronavirus appears to have followed a similar trajectory.
But this is no reason to panic. This coronavirus has already demonstrated itself to be less virulent than either SARS or MERS. Current reports are placing the overall case fatality rate of the novel coronavirus at around two percent, with most of the fatalities occurring in the elderly or those already seriously ill from other causes (the same populations susceptible to, for example,mortality from the flu). A major issue with emerging viruses is that virus detection is often skewed to more severe cases, leading to early spikes in panic before more case reports come in. Those with milder illness may not seek medical treatment, resulting in an artificial inflation of fatality rates. On one hand, this means that the novel coronavirus may have an even lower mortality rate than two percent.On the other hand, cases of this coronavirus could be going undiagnosed. Of course, the obvious downside to undiagnosed cases is increased transmission, as those who present mild or subclinical symptoms will continue to go to work and school, potentially spreading the virus. But counteracting this, there is a link between milder disease and reduced viral replication which may reduce the risk of viral spread in these cases. For example, with SARS, transmission occurred primarily from patients with more severe, recognizable illnesses, as it infected the lower respiratory tract rather than the upper airway. The novel coronavirus uses the same cell surface receptor as SARS, so researchers are predicting that transmission will occur primarily from patients presenting more severe symptoms of lower respiratory tract infection. Reports have suggested that symptoms manifest between two days and two weeks after exposure, and that the virus is contagious during its incubation period, at around two weeks after exposure, once symptoms have become identifiable.
So, how can we best protect ourselves? The novel coronavirus infects the respiratory tract, and so it follows an airborne transmission route, primarily through large droplets, contact between people, or contact with live or dead animals in environments like wet markets in regions where the virus has been identified. Symptoms of this novel coronavirus include fever, cough, and difficulty breathing leading to pneumonia-like symptoms in more severe cases. The most effective precautions involve those commonly taken against the flu or common cold: regularly washing your handsand avoiding touching your mouth or anywhere else on your face.Covering your mouth when you sneeze or cough and staying home when you feel ill also help slow viral spread. Face masks, which have been flying off the shelves recently, can also be a useful precaution, but there are a few important caveats. The most common type of mask, which is essentially a sheet fitted over the mouth and nose (as worn by dentists), is only effective insofar as it prevents you from touching your face with unclean hands. It can only block the largest droplets and will not prevent the majority of airborne viral particles from getting through. For that, you’d need a proper respirator, of at least the N95 variety, but these generally aren’t necessary on a day-to-day basis, unless you’re a healthcare professional or otherwise at high risk of contact with sick people or are yourself sick.It is important to speak to healthcare professionals or check resources provided by Public Health Canada or other public health agencies if this information changes as we learn more about the virus.
The most important measures to be taken against novel coronavirus will be implemented on a much larger scale as countries work together to break the viral transmission cycle worldwide. Already, there has been impressive mobilization and collaboration, as researchers in China managed to sequence the virus in a number of days and released it for international access, and public health workers have documented and shared case report data. Public health agencies have worked together to decide on protocols for quarantine, hospital-building, and other projects. Following the SARS outbreak in the early 2000s, countries around the world, notably China, have put immense work into strengthening their public health infrastructure to prepare for a situation like this. As of January 30, theWorld Health Organization has declared the novel coronavirus a public health emergency of immediate concern. What this entails is the WHO has been careful to delineate, chiefly involves preventing the virus from reaching countries whose public health systems are less equipped to deal with it.
I would like to end this piece with a note on fear. At the risk of sounding didactic, I would suggest that you ask yourself, “Is my fear proportionate to the risk I am facing?” In context-appropriate doses, fear can sometimes be helpful—it can keep you alert and aware. At the very least, taking more stringent hygiene measures might protect you from getting the regular flu. If you are here in Canada reading this, your personal risk is incredibly low. As of February 2, there have been a total of four cases of novel coronavirus reported in Canada, with no fatalities and no reported human-to-human spread. Of course, personal risk isn’t the only component, and the last thing I want to do is dismiss fear for family and friends who may be located in and around outbreak epicenters. What I do want to note is that as fear scales out of proportion with risk, it can begin to warp your perception of that risk, as well as the world around it. Who might be affected by your fear? Who is profiting from it, and who might you be harming?As media-fueled public hysteria over the novel coronavirus mounts, contrary to evidence of its relatively low virulence, and contrary to the robust public health efforts being made to slow its spread, fear has latched onto and fed a xenophobia possibly more dangerous than the virus itself.
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