Coronavirus And The COVID-19 Pandemic
Coronavirus And The COVID-19 Pandemic
An introduction to the virus that changed everything
Author: L. Joby Morrow, M.D.
April 21, 2020
An organism less than a millionth of a meter long has managed to stop the world in its tracks. The recent outbreak of a virus previously unknown to humanity has caused countries all across the globe to shut down, and has ground much of the world’s economy to a halt. This tiny particle has dominated news coverage worldwide since late February 2020, and it shows little sign of slowing down. It’s a new and powerful coronavirus, and it has struck fear into much of the population. But what is the coronavirus, and why is it so powerful? In many ways, the virus acts just like any other virus; in other ways, the coronavirus is in a class of its own. By increasing your understanding of how the coronavirus works — how coronavirus spreads, how the coronavirus virus attacks cells and how COVID-19 is diagnosed and treated — you, along with the rest of the world, can get a bit closer to a more normalized and peaceful reality.
What is Coronavirus?
By now, you've undoubtedly heard of the coronavirus. It is, by far, the most dominant topic of conversation among friends, family and colleagues and it is the most covered topic in the news in the history of humanity. It even has its own grammatical variations: corona virus, COVID-19 virus or even just “Rona” in informal use. But exactly what is coronavirus?
To answer the question, you’ll need to know about viruses more generally. Viruses are tiny particles which infect living cells and can only reproduce inside those cells. They have their own genetic material used to make copies of themselves. Viruses have likely been around as long as there has been life on the planet. In that sense, viruses are “alive.” However, viruses don’t have a metabolism — they don’t use or produce energy, and they don’t have cells. They require the cells of living organisms for their energy and reproductive functions. Because of those features, viruses aren’t thought of as being fully “alive.”
Viruses vary in shape and size, but all of them have the same general components: a group of proteins held together by a thin layer of fat, all of which surrounds the genetic material the virus uses to make copies of itself. Over time, these viruses have extremely well adapted to figuring out how to reproduce.
Characteristics Of Coronavirus
Coronavirus is the name one of several different groups of these viruses. The coronavirus family has some distinguishing features: the proteins on its surface spike out from the center of the virus, making it look like a crown, or perhaps the halo formed by a solar eclipse, when viewed under a microscope. In Latin, “corona” means “crown” (think of the coronation of king or queen), and that’s how the coronavirus got its name. All coronaviruses have a single strand of ribonucleic acid, or RNA, to use as genetic material so that viruses can build and reproduce themselves.
Electron microscope image of SARS-CoV-2, the virus responsible for COVID-19
Courtesy: National Institute on Allergy and Infectious Disease (http://www.niaid.nih.gov)
Types Of Coronavirus
There are several different strains in the coronavirus family, and all of them typically cause respiratory diseases. One strain causes the common cold, which usually affects the upper parts of the airway (rather than the lungs, in the lower part). Two other strains of coronavirus have been in the news in the last few years, because they also caused large outbreaks of disease that primarily affects the lungs: severe acute respiratory syndrome coronavirus 1, or SARS, and Middle Eastern respiratory syndrome coronavirus, or MERS. A few coronavirus strains only infect other mammals and birds and do not infect humans.
The COVID-19 Coronavirus
The virus that is responsible for the 2019-2020 pandemic is new to humanity. It is widely believed that the virus was transferred to a human from an exotic animal at a live animal market in Wuhan, China in December 2019. Since it was new to humans, it was originally called the “2019 novel coronavirus”, or 2019-n-CoV. When scientists studied the virus, they noted strong similarities to the SARS virus, and caused respiratory symptoms similar to those of the SARS and MERS viruses. An international group of scientists gave the virus the name severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2. The disease that results from infection with SARS-CoV-2 is called coronavirus disease 2019, or COVID-19 for short.
Scientists and physicians use the name SARS-CoV-2; media and people in more casual settings usually refer to the virus as the coronavirus, the COVID-19 coronavirus, or simply by the name of the disease it causes, COVID-19. This is similar to the way people sometimes interchangeably use the terms “HIV” and “AIDS” to describe the human immunodeficiency virus that infects cells to cause acquired immune deficiency syndrome.
How Does The Coronavirus Spread?
Since they lack the ability to make copies of themselves, all viruses hijack the energy and machinery of living cells for reproduction. There is one major way that the COVID-19 coronavirus accomplishes this feat: like all coronaviruses, it attacks and infects respiratory cells. During a cough or a sneeze, or even during normal breathing, some of the billions of virus particles (along with the cells they’ve infected) get dislodged and hitch a ride in the water vapor leaving the body. The larger the droplet of water, the more virus particles can travel in it. Mucus can create the same effect, since it also contains droplets, respiratory cells and many virus copies.
These virus-containing respiratory water droplets leave the body and land on surfaces like table tops, silverware and computer keyboards. When the COVID-19 coronavirus is on these surfaces, it doesn't cause any damage by itself. It can’t reproduce, and it can’t infect anything else. Many, though not all, of the virus particles begin falling apart after a few hours of not being inside of a cell.
The damage starts when human hands touch one of these droplet-containing surfaces. When a hand has come into contact with droplets containing virus, and that hand then touches a section of the body that is connected to the respiratory system, the virus then has a route to infect another human. On average, each person infected with the coronavirus causing COVID-19 infects two to three more people, though initially one person infected five people or more. Most commonly, infection involves direct contact:
- Hand to eye
- Hand to nose
- Hand to mouth
- Mouth to mouth
The COVID-19 coronavirus particles must get access to respiratory cells; no other cells have the docks that the viruses need to enter and reproduce. However, there is evidence that the COVID-19 coronavirus is able to travel for up to three hours in droplets which get aerosolized (sprayed into the air).
How Does The Coronavirus Work?
Now that you have a sense of the features of the coronavirus and how it spreads, it will be easier to understand how the coronavirus works. This will help you understand why the COVID-19 coronavirus can create such severe respiratory disease.
The spikes on a coronavirus that give it that crownlike appearance are where the COVID-19 virus does its damage. The virus particles are like ships, and the spikes on these particles have a small region on them that docks into a port on a respiratory cell. This port is a protein called angiotensin converting enzyme II, or ACE 2. When the virus anchors into the ACE 2 port, the surfaces of the virus and the cell change shape and merge together. That allows the genetic material inside the virus to get into the cell, like Vikings landing in a country they intend to raid.
Once inside the cell, the virus’s genetic contents — the bloodthirsty Vikings — travel upriver in small sailboats up to the capital city of the cell: the nucleus. This is where cells govern themselves: where the cell keeps the instructions to go about its daily tasks, where it directs the materials that keep it healthy and where it begins reproduction.
As the virus’s genes enter the nucleus of the cell, the virus shuts down the cell’s production factory for the cell’s genetic material, reprogramming it to make viral genetic material instead. That action allows the virus to make all the components it needs to clone itself: the genes, the layer of fat surrounding the genes, a protein to fuse with the cell, and the spike proteins it uses for docking.
The virus clones itself like this millions of times at the cell’s expense, before bursting out of the nucleus and the cell, sometimes killing the cell or damaging it so badly that the cell hits its own “self-destruct” button. Now, all of these millions of new viruses are ready to infect new cells, and the cycle repeats.
How Coronavirus Becomes COVID-19
As the damage from coronavirus infections mounts, the infected cells send out distress signals. These signals alert the entire body that it is under severe attack. The immune system, the body’s homeland security and military, gets activated, and goes out looking for the virus using its recognition system. The immune system prepares itself to mount an all-out assault on its viral enemy; this counterattack is called the inflammatory response.
One of the first ways the immune system responds is by literally turning the heat up on the virus in the body, resulting in a fever. This is your system’s way of trying to make an unwelcome environment for the coronavirus. A fever also helps the rest of your body know that there is a problem.
Next, the body brings in the ground troops. First up is the scout team. The rangers are known as antigen presenting cells, or APCs. The APCs size up the enemy virus, neutralize it where it’s possible, and bring back reconnaissance photos to their commanding officers, who begin making targeted counterattack weapons based on the recon: antibodies. The information gets sent further up the chain to central command, where the immune system manufactures cells and other high-caliber antibodies designed specifically to target the coronavirus.
Unfortunately, though, the body’s inflammatory response process is messy, and it creates a lot of damage. Often, that damage is worse than that of the initial viral infection. The destruction induces leaks in the blood supply of the respiratory cells, which then spill out watery fluid. That fluid mixes with all the carnage and debris from cells and antibodies fighting viruses, and accumulates in the air spaces of the lungs. That action results in more difficulty breathing, coughing and the other usual symptoms of pneumonia. The more immune damage, the more severe the COVID-19 pneumonia.
Testing for COVID-19
Tests for COVID-19 come in two forms: a test for the genetic material of the coronavirus, and a test for the antibody (the immune system scout team weapons). To diagnose COVID-19, doctors look for the genetic material of the coronavirus (an at-home diagnostic test was recently authorized for use in the United States, with more expected; several other countries have offered at-home testing since March 2020). That genetic material of the virus disappears after the infection clears.
Most of the time, when the body’s immune system has created antibodies to a virus after an infection, the body can no longer be effectively attacked by that virus again. This is called immunity. A vaccine works by giving humans weak or inactivated parts of a virus for antibodies to create immunity, bypassing the need to get infected. Vaccines against the COVID-19 coronavirus are being developed around the world by governments and pharmaceutical companies in cooperation.
As of April 2020, there aren’t any approved medications to treat COVID-19. Dozens of medications are undergoing clinical trials to test their effectiveness. Among those, a drug meant to treat Ebola virus disease is one of the most promising, along with deferoxamine, an iron binding supplement. Though highly touted, hydroxychloroquine and azithromycin have not shown consistent effectiveness at reducing symptoms or severity of disease in clinical studies.
The symptoms of COVID-19 — most often fever, cough, and severe fatigue — are managed according to their severity. Prolonged fever tends to lead to dehydration, so patients are encouraged to drink fluids as much as possible. When patients have severe COVID-19, they require hospitalization and need fluids intravenously. Critical COVID-19 means that patients require a ventilator. If patients continue to decline or do poorly while in critical condition, they can be given blood plasma (the part of blood with the cells in it) from another person who has made antibodies to the novel coronavirus. That intervention has shown to be effective in people who are critically ill.
Prevention of COVID-19
One of the most effective ways to prevent COVID-19 is handwashing. Soap destroys the fat layer that holds virus proteins together, and the virus disintegrates. Alcohol that is at least 60% by volume also destroys this fat layer; thus hand sanitizer and some other types of alcohol are effective in killing coronavirus, along with several disinfecting products.
Facial cloth masks have been shown to reduce the spread of virus particles from individuals who show no symptoms. More sophisticated masks like surgical masks keep smaller droplets out, and thus offer more protection. Masks like N95 are designed to fit closely to the face and can filter 95% of particles.
From a societal point of view, in order to prevent widespread infections of the COVID-19 coronavirus, the virus must undergo one of four scenarios:
- Humans must place themselves in relative isolation from each other to prevent transmission (social distancing, or physical distancing)
- More than half of the population must get the virus and develop antibodies, which slows down the transmission of the virus person to person (herd immunity)
- The virus must be isolated to a group that has already had it or is likely to get it (containment)
- A drug must be created to mimic the effect of an infection (vaccine)
With millions of cases worldwide and growing by tens of thousands per day, the COVID-19 coronavirus is likely here to stay. Cases are likely to keep growing until either an effective and accepted vaccine is developed or a new therapeutic drug shows consistent effectiveness. The presence of this new virus will test the world’s ingenuity and cooperation in ways as profound as the way that the virus has changed the world’s economic and political balance. With accurate and detailed information, patients, health care providers and the public will be more equipped to meet the challenge that the novel coronavirus presents.
L. Joby Morrow received his MD from UC Davis in 2005 and completed his residency in family medicine and psychiatry in 2010. Currently, Morrow is the senior medical writer, medical editor and healthcare consultant at Coquí Prose, where he has worked for 2 years.
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