Brian Plonka / For The Spokesman-Review
Brian Plonka / For The Spokesman-Review
It thrives inside of us, miniscule and hidden, and travels to others on invisible pathways.
It arrives without our knowing it and begins to reproduce, to kill healthy cells, to sicken. It flows outward on waves of exhalation – waves of breath, of sneezing or coughing, of speaking or shouting or singing – into the air that others breathe.
It repeats and repeats, this cycle of our infinitesimal adversary, journeying along the unseen points of contact.
Looked at in a certain light, you’d have to call it a miracle.
An ugly, insidious miracle.
• • •
Seen up close, SARS-CoV-2 is a Seussian thing.
It is far too small to be captured by a regular microscope – far tinier than the tiniest wave of light. At roughly 100 nanometers across, you could line up 10,000 of them in the millimeter space on a ruler.
Using one kind of electron microscope – the Scanning Electron Microscope – scientists can produce images of the virus as it exits and enters human cells, clustering ominously, preparing to spread.
With an even deeper imaging technology, the Transmission Electron Microscope, they can make pictures of the virus that show its main, globular body – the envelope in which the genetic material that will direct its growth is stored – surrounded by the fuzzy, spiky corona that gives it its name.
That spiky corona – it’s the key to the whole operation.
It’s also the key to shutting it down.
• • •
To understand the novel coronavirus is to be reintroduced to the astonishing ways of the world. It is to be reminded of the unimaginable scale of the universe, which operates at levels more vast and more minute than we can truly grasp.
When it is breathed into the body, a particle of the novel coronavirus – a not-quite-living thing looking for a way to thrive – finds a home first in the healthy tissue of the throat and upper respiratory system. In this way, it is like other such viruses that cause colds or flus.
But the “evil genius” of this particular pathogen – to use the words of virologist and author Peter Kolchinsky – is that it remains in the throat for days without making itself known.
That is what makes this version of SARS – severe acute respiratory syndrome – different and more dangerous than the SARS outbreak in the early 2000s. Kolchinsky detailed this difference in a long Twitter thread that summarized research discoveries about the virus.
The first SARS moved quickly into the lungs, where it made people very sick very quickly. Those infected showed severe, obvious symptoms right away and were quarantined, containing the spread.
This virus hangs around quietly in the throat and mouth for days, ready to ride outward on the respiratory droplets of the breath. A person can be infected for 48 hours without symptoms, and for days longer with only very mild symptoms.
Only then might it migrate to the lungs, where it can cause severe illness and death, just as the first SARS did.
All that hidden time in the throat, which operates as a launching pad for outward respiration – that’s what makes COVID-19 so insidious.
Many of those infected will only have a mild case, but many, many people will be infected along the way.
Which means the global death toll – over 1.5 million and rising – is massive.
• • •
An artist’s rendering of the virus shows that the fuzzy corona surrounding the viral body is made up of long protein spikes. These spikes attach to protein receptors on the surfaces of healthy cells and allow the virus entry.
Like a key fitting a lock.
Our cells are covered with these protein receptors, and they facilitate interactions with many different kinds of particles, fueling the cell-messaging that runs so many functions in the body.
The virus slinks among healthy cells, looking for a lock that matches its key. When it does, it moves right in, where it hijacks the healthy cellular functions and begins making copies of itself.
By the time it’s done, tens of thousands of new viral particles have been set loose, and the healthy cell is dead.
If you’ve seen mob movies or TV shows, you’re familiar with what’s known as a bust-out. Here’s how a bust-out was depicted on “The Sopranos”: The mob took over a sporting goods store whose owner could not repay his ever-growing loans.
The wise guys ran up the store’s credit, raided its assets and gutted it. They turned the ordinary, healthy purpose of the enterprise toward their own ends, and left it bankrupt.
That’s what a virus does to a cell. It’s a bust-out.
• • •
From the throat, it’s a pretty quick trip back out into the air.
Coughing and sneezing. Singing and shouting. Even regular breathing can help carry forth the virus, trapped in the respiratory droplets.
The main viral journey seems to follow the pathway of larger respiratory droplets, which spray outward but fall to the ground over the course of several minutes. Loud speech sends thousands and thousands of such droplets into the air. When we stand near others, unprotected, we’re much more likely to breathe in the virus than we are when we stay far enough apart that our droplets don’t intermingle.
Wearing a mask cuts down on the outbound flight of our respiratory droplets significantly, which is why we wear them.
Not necessarily to protect ourselves, but to protect others.
The virus also travels in much smaller respiratory droplets that are aerosolized, which means they may remain suspended in the air for hours. There has been disagreement about how much transmission occurs this way; the CDC says most transmission comes from the larger droplets, but that transmission via aerosolized particles is possible.
It’s also possible, though believed to be less common, for the virus to spread by surface contact. What seems true now is that the most fertile realm for the virus is the Venn diagram where people’s respiratory realms overlap – where people stand close enough to inhale tiny, invisible bits of each other’s respiration.
Thus, the 6-feet social distancing. The hand-washing. The mask.
Thus the urgent calls for us to stay away from each other, for now.
• • •
After the viral particle hijacks a healthy cell, it produces thousands of new viral particles that exit the dying cell, each looking for the right lock. The cycle repeats thousands and thousands of times.
Unlocking the cell. Making more virus. Busting it out.
The virus mutates along the way, making it even harder for the body to fight it. It leaves dead cells in its wake, which, in combination with the effects of the immune response, produce the symptoms of COVID-19.
The body sends out its defense teams, naturally, and the progression of the illness is determined by the ensuing cellular warfare. In the first wave of immune response, the body secretes a series of protein molecules known as cytokines to fight the virus. These cells are part of the body’s general, first-wave immune response – it’s the team of pathogen-fighters that responds to any infection.
Interferon is one form of cytokine – it stimulates an infected cell, prompting it to produce proteins that interfere with viral replication. Other cytokines produce messaging responses to rally other defensive responses.
It is, ironically, this immune response, and the attendant inflammation, that produces the symptoms and health consequences of the disease. Cytokine activity, for example, is associated with flu-like body aches.
And in some of the worst COVID-19 cases, a serious overreaction of the immune system – called a “cytokine storm” – produces the most severe symptoms and even death.
After several days of cellular conflict, the body produces a second wave of immune response, sending in teams of white blood cells that are specialized to fight this particular virus.
• • •
In the midst of all this invisible activity, people with COVID-19 might experience an incredibly various set of symptoms.
Most have mild illnesses with symptoms not unlike those of a flu or cold – fever, cough, headache, shortness of breath, body aches, nausea – and recover in a couple weeks. Many have no symptoms at all. Some unusual symptoms are common, such as a loss of taste or smell and the presence of pink eye in more severe cases.
The journal Science organized the most common symptoms into six clusters: flu-like illness with no fever; flu-like with fever; mainly gastrointestinal sickness; severe respiratory symptoms with fatigue; severe respiratory symptoms with confusion; and a combination of severe respiratory and gastrointestinal symptoms.
And yet, a variety of surprising combinations and puzzling symptoms continue to add up. Some infected people have had long illnesses far out of the ordinary. Most children are less susceptible, but there have been very serious cases among kids. It’s not yet clear whether people can be reinfected once they’ve recovered. With a new virus spreading exponentially, the unknowns mount.
In the worst cases, the virus migrates to the lungs and spreads widely, overwhelming the immune response, and the resulting cell death limits lung function, fills the air sacs with fluid and cellular debris. Pneumonia is a common result.
But the disease also attacks other organs in the body, including the heart and brain, in ways that are still not fully understood.
The disease can be serious and even fatal for healthy people, but those whose health is compromised – by age or underlying conditions – are at the most risk for the worst consequences.
• • •
When the body sends in the second team of virus-fighters, it is comprised of two types of white-blood cells: T-cells and B-cells.
T-cells attack the cells that have been taken over by the virus and kills them. They also stimulate the production of the B-cells, which produce an antibody specifically to fight the virus.
And therein – in the invisible machinations of another miniscule astonishment – lies the hope for controlling the virus.
Remember the spiky corona? The lock-and-key?
The antibodies produced by B-cells block that process. They bind to the virus’s key and render it unable to attach to the cell.
This process, repeated and repeated, is one of the ways that infected people drive away the virus. As it does so, most of the T-cells and B-cells fade away.
But some remain, and these “memory cells” prepare the body to recognize and fight off the virus if it returns, by producing the antibodies that prevent the viral key from fitting into the cell’s lock.
Such memory cells are the foundation of vaccine prevention. Vaccines essentially imitate an infection, resulting in the production of memory cells in the vaccinated person.
This is the way the flu vaccine works. It’s the way measles and polio vaccines work. There are reasons to think we’ll have a coronavirus vaccine in the not-too-distant future – a shot that will help disable these viral keys before they ever find a lock.
A miniscule miracle of science, to combat the dark wonder of the virus.
When that day comes, we’ll all breathe easier.
• • •
This piece was written based on information from the CDC, WHO, Science, Scientific American, and several other research papers and journalistic summaries of research papers, and with assistance from Mark Singer, senior epidemiologist at the Spokane Regional Health District.