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Facts About Coronaviruses and Reducing the Risk of Infection

Linda Crampton is an experienced teacher with a first-class honors degree in biology. She writes about the scientific basis of disease.

A picture of coronavirus virions (individual entities) as seen through an electron microscope; the virus is known for the spikes on its surface

A picture of coronavirus virions (individual entities) as seen through an electron microscope; the virus is known for the spikes on its surface

Coronaviruses and Their Effects

Coronaviruses are interesting and sometimes dangerous entities that infect humans and other animals. They often make us sick, but the severity of the illness varies. The infection may be minor, resulting in symptoms that are no more serious than the common cold. Sometimes it's potentially deadly, however. A coronavirus disease known as COVID-19 is currently of global concern.

Viruses can change over time as they gain, lose, or change genes. The genes are responsible for the characteristics of the virus. Every now and then, researchers announce that a novel variety of coronavirus has been discovered. Examples of varieties that have caused problems include the ones responsible for SARS (Severe Acute Respiratory Syndrome), MERS (Middle East Respiratory Syndrome), and COVID-19 (coronavirus disease 2019). Though the virus that causes the last disease was discovered in late 2019, it became a major problem in 2020 and is still a concern today.

Health agencies around the world are tracking the spread of coronaviruses carefully. In this age of frequent international travel, infections can easily spread from country to country. Luckily, there are things that we can do to significantly reduce our chance of catching a virus. There are also ways in which we can boost the activity of our immune system, which protects us from infections.

A bacteriophage or phage is a virus that infects bacteria. Here a phage is injecting its nucleic acid into a bacterium. The nucleic acid contains the genes of the virus.

A bacteriophage or phage is a virus that infects bacteria. Here a phage is injecting its nucleic acid into a bacterium. The nucleic acid contains the genes of the virus.

Features of a Virus

Viruses are very different from other living things. In fact, some scientists don't consider viruses to be alive. Unlike living organisms, they aren't made of cells. Instead, they consist of a core of nucleic acid (DNA or RNA) surrounded by a coat of protein. The protein coat is known as a capsid. Some viruses, including coronaviruses, have a lipid envelope surrounding their capsid.

Another difference between viruses and cellular organisms is that viruses can't reproduce on their own. They must enter a cell of a living organism in order to make new copies of themselves.

Although a virus has a simpler structure than a cell, it's still impressive. It has the amazing ability to trick the cells that it infects. It not only passes through the protective membrane surrounding a cell but also stimulates it to make virions (viral nucleic acid surrounded by a capsid, or individual virus particles) instead of the cell’s own products. The virions then destroy or damage the cell as they enter the outside world.

Multiple bacteriophages surround a bacterium.

Multiple bacteriophages surround a bacterium.

How Does a Virus Get into Cells?

The "goal" of a virus is to send its nucleic acid into a cell. The nucleic acid contains genes that encode the instructions for making new virions.

Viruses seem to have three ways of accomplishing their goal. Each method requires a virion to bind to receptor proteins on the cell membrane before an infection begins.

  • Viruses that infect bacteria (bacteriophages) inject their nucleic acid into a bacterium while leaving their capsid outside.
  • The lipid envelope of some viruses fuses with the cell membrane, which is also rich in lipids. The capsid and nucleic acid are then released into the cell.
  • Some viruses enter cells by a process called endocytosis. The cell membrane forms an invagination or pocket that engulfs and surrounds a virion. The pocket then separates from the cell membrane, forming a sac with the virion inside. The virion later breaks out of the sac.

Researchers are studying the mechanisms by which harmful viruses attach to the protein receptors on the outer surface of a cell membrane and then enter the cell. If they are able to understand the details of this process in a specific virus and can interfere with it, they should be able to stop an infection.

One method by which coronaviruses enter cells is by receptor-mediated endocytosis.

One method by which coronaviruses enter cells is by receptor-mediated endocytosis.

Viral Reproduction and Exit

Once inside the cell, the nucleic acid of the virus take over its equipment, causing the cell to make new viral nucleic acid molecules and new protein coats. The virions are then assembled.

The virions may burst out of the cell, destroying it in a process called lysis. In some types of virus, however, the virions are released through the cell membrane in a gentler process. These additional methods still damage the cell, however, and usually kill it.

One "gentler" method by which virions leave cells is called budding. In the budding process, a virion produces a bud-like swelling on the cell membrane. As the bud splits off, a bit of broken cell membrane surrounds the released virus particle. This is the method by which many viruses get their lipid envelope.

Another method of viral release is called exocytosis, which is the opposite process to endocytosis. A vesicle (sac) carrying the virion fuses with the cell membrane and releases its contents to the outside environment. Coronaviruses are released by exocytosis.

Viral entry, reproduction, and exit are complex processes. Many details of the processes still need to be discovered. The benefits obtained from the discoveries could be wonderful, since viruses cause diseases in humans, animals, and plants. Understanding viral behavior could lead to new treatments for these problems.

A colourized photo of the HIV-1 virus (green) budding from a type of white blood cell called a lymphocyte (blue).

A colourized photo of the HIV-1 virus (green) budding from a type of white blood cell called a lymphocyte (blue).

Structure of Coronaviruses

A coronavirus is named for its appearance under an electron microscope. The virions are covered by club-shaped projections or spikes made of protein. These reminded early observers of a crown or the rays of the sun's corona. "Corona" is the Latin word for crown.

A coronavirus virion has an irregular shape but is often roughly circular. It contains a single strand of RNA, or ribonucleic acid, which is helical and contains genes. The human body contains RNA too, but our genes are present in DNA, or deoxyribonucleic acid. The genes of other organisms and of many viruses are also present in DNA. The RNA molecule of a coronavirus virion is large and is surrounded by a protein capsid. This is in turn surrounded by an envelope made of lipid. The protein spikes protrude through the envelope.

A colourized transmission electron micrograph of three MERS virions

A colourized transmission electron micrograph of three MERS virions

A Coronavirus Infection

Coronaviruses are transmitted in droplets released from the respiratory system. We release these droplets as we sneeze, cough, or speak. It's thought that the viruses are also transmitted though personal contact, such as by shaking hands. In addition, a person may become infected when they touch a contaminated surface.

Coronaviruses cause problems in the upper respiratory tract, but most of them don't produce a serious infection. The usual symptoms resemble those of the common cold and include a runny nose, sneezing, coughing, a sore throat, and a fever. Most people have been infected by a coronavirus at some time. There may be multiple incidences of infection in a person's life. The affected person usually recovers without help.

Coronaviruses may sometimes cause problems in the lower respiratory tract, such as pneumonia. These problems generally occur in people who have a weakened immune system or in elderly people. In some cases—especially in children—the viruses cause problems in the digestive tract.

Antiviral drugs are available to treat some viral infections, but most can't be cured by drugs. Doctors have to treat the symptoms rather than the infection itself. They can prescribe medications to reduce fever, relieve pain, and make breathing easier, for example. Although the body generally has to destroy the virus on its own, medical support can be very helpful.

While most coronaviruses cause relatively benign infections, some can cause serious symptoms and may be deadly. The SARS virus and the MERS virus are examples. Their full names are SARS-CoV and MERS-CoV, where CoV stands for coronavirus.

The SARS Virus, or SARS-CoV

The first appearance of the SARS coronavirus was during a disease outbreak in 2002-2003. The last case of SARS was diagnosed in 2004. Like the MERS virus today, the SARS one was called a "novel" coronavirus because it was a new variety that had never been observed in humans before.

The first symptom of the infection was usually a high fever. This was often followed by a headache and body aches. Serious respiratory problems often developed, including pneumonia. Diarrhea was sometimes present, too. According to the World Health Organization, or WHO, 8,098 people were diagnosed with SARS and a total of 774 people died.

It’s interesting to note that the CDC (Centers for Disease Control and Prevention) still uses the present tense to refer to the virus, though they do say that they are no longer updating their page about SARS. They haven’t deleted it, though. They acknowledge that no cases have been reported anywhere in the world since 2004. Hopefully, the virus has disappeared. Unfortunately, other coronaviruses that can hurt us still exist.

The MERS Virus, or MERS-CoV

The MERS coronavirus, or MERS-CoV, was first observed in 2012 in Saudi Arabia. Researchers know that it's potentially dangerous, but they still have much to learn about the virus. The data below was current when this article was last updated. Since statistics can change, the World Health Organization's website should be checked for the latest information. A link is provided in the "References" section below.

According to WHO, from 2012 to approximately the present time:

  • 858 "known" deaths from the infection had been reported to the organization.
  • The MERS virus had been found in 27 countries. (The infection is most common in countries in and near the Arabian peninsula. So far, people in other countries with the disease have recently visited this area.)

The death rate from the infection (35%) might be a concern. WHO says that it may be lower than believed, however. Infected people without symptoms or with only minor ones may not be diagnosed with MERS and are therefore not included in the statistics. In addition, health agencies say that the current risk of infection is low for residents of North America. The CDC says that at the moment only two cases of MERS have ever been diagnosed in the United States. Both patients were healthcare workers and likely became infected in Saudi Arabia. They were treated in hospital and recovered from the infection.

Health officials are aware of the potential for the virus to spread globally and are continuing to monitor the situation. They also say that we should follow the recommended procedures for reducing the chance of a viral infection. These procedures are described below.

The virus does not seem to pass easily from person to person unless there is close contact, such as occurs when providing unprotected care to a patient.

— WHO (World Health Organization)

Transmission of the Disease

The transmission of the MERS virus is not well understood. It seems to pass from one person to another through close contact but probably not from casual contact. It may be transmitted via camels as well. The virus has been discovered in camels and some people have become sick after handling the animals. This doesn't prove that camels can transmit MERS to humans, though.

WHO recommends that people wash their hands before and after approaching camels and that they avoid animals who are obviously sick. They also recommend that people avoid eating or drinking raw or undercooked camel meat, milk, or urine. (Yes, some people do drink camel urine.)

People who visit countries with MERS cases need to make sure that they take steps to avoid infections. The majority of these countries are located around the Arabian Peninsula. In 2015 an outbreak occurred in Korea, however. According to the CDC, so far this has been the largest outbreak of the disease outside the peninsula. It originated from a traveller returning to Korea from an infected area. The WHO web page mentioned in the "References" section below is useful for travellers because it contains the latest news about MERS outbreaks.

Possible Symptoms and Treatment

Like the SARS virus, the MERS one produces symptoms beyond the respiratory system. In people who get sick from the infection, the patient generally has a fever, shortness of breath, and a cough. The respiratory system symptoms may be severe. The patient may also experience diarrhea, nausea, and vomiting. Possible complications include pneumonia and kidney problems.

Some people don't get sick when they're infected by the MERS virus or experience only mild symptoms that resemble those of a cold. According to the CDC, older people and people with pre-existing medical conditions may be more likely to experience severe symptoms. These conditions include:

  • a weakened immune system
  • a chronic lung disease
  • diabetes
  • kidney disease
  • cancer

At the moment, there is no specific treatment for MERS. Medical care is very important, though. Doctors can support the patient's recovery by relieving symptoms and protecting vital organs.

The COVID-19 Pandemic

In January, 2020, the discovery of a novel strain of coronavirus in China was reported. The strain was at first called 2019-nCoV because it was discovered at the end of 2019. The "n" means novel. The current name of the virus is SARS-CoV-2. The name of the disease that it causes is COVID-19. The virus has spread to multiple countries. Its name shows that it is related to the first SARS virus.

At the time when I last updated this article, 529 million people in the world had been infected by the virus and 6 million people had died from the infection. Fortunately, new cases are currently decreasing. Hopefully, the cases will continue to decline. The decline is probably not of much comfort to someone who is seriously affected by the virus, however.

The virus seems to produce relatively mild symptoms for many people or even no symptoms at all, but in some cases it produces a disease that resembles pneumonia and is more serious. The rate at which the virus has spread around the world is a concern, as is the rate at which it is mutated (changing its genetic features and resulting characteristics).

There are still many unknown factors about the virus and the disease. The death rate may be lower than suggested because many people may have a mild version of the disease. Some infected people apparently have no symptoms. Both of these groups may never realize that they have a coronavirus infection because they don't seek or receive a diagnosis. Statistics such as these wouldn't be reported by WHO. On the other hand, some worrying reports about the potential effects of the virus have appeared. Some people appear to have long-term effects from the infection. More research is needed to understand the situation.

The risk of serious disease seems to increase with age, but this doesn’t mean that younger people are immune to the effects of the virus. Sadly, elderly people are most susceptible to the infection, but people in all age groups have experienced serious effects from the illness and have died.

Researchers around the world are working hard to find the best antiviral substances to fight the SARS-CoV-2 virus and to provide the most effective vaccines to prevent the disease that it causes, which is a hopeful sign.

An Epidemic and a Pandemic

The World Health Organization is currently releasing daily situation reports containing the latest disease statistics related to COVID-19. These reports can be accessed via the fourth link in the "References" section at the end of this article. The outbreak is still in progress, and statistics are changing on a daily basis.

WHO is monitoring the situation carefully. On March 11th, 2020, they classified the coronavirus outbreak as a pandemic. An epidemic is widespread but affects a limited region, such as one country. A pandemic affects many countries. Hopefully, as vaccination becomes more common, the number of cases will continue to decrease.

Washing the hands with soap for twenty seconds is important for preventing infections.

Washing the hands with soap for twenty seconds is important for preventing infections.

Reducing the Risk of Infection

There are a variety of ways in which people can greatly reduce the chance of getting sick from a viral or a bacterial infection. The steps can also reduce the chance of infecting someone else. Here are ten suggestions that are recommended by health agencies.

  • Wash hands frequently, especially before eating and after a high-risk event such as using a bathroom.
  • Wash hands for at least twenty seconds per session. One common suggestion that may be helpful for children (and perhaps for adults too) is to wash the hands for as long as it takes to sing "Happy birthday to you" twice.
  • Use soap and water to wash the hands, but if these aren't available, use an alcohol-based hand sanitizer instead.
  • Wash or disinfect objects that are touched frequently, such as door knobs, faucet handles, and toilet flushers.
  • Flush toilets when the lids are down to avoid contact with the spray that's released and to prevent the germ-laden spray from spreading through the air.
  • Consider using a towel with a different colour or pattern for each family member. This will reduce the chance of an infection passing from one person to another.
  • Don't touch your mouth, nose, or eyes. This requires some practice, as I've discovered myself. You should begin "training" yourself while you and your acquaintances are healthy so that you are prepared if a virus reaches your community.
  • If you have to touch your face to wipe your nose with a tissue (for example), immediately throw the tissue away and then wash your hands.
  • Avoid close contact with people if they are obviously sick. During the height of the pandemic, health professionals recommended that we use social distancing around other people even if they appear to be healthy.
  • Cover your mouth or nose when you sneeze—but not with your hands, which can transfer the germs to other surfaces when you touch them. Use a tissue. If you don't have one, sneeze (and cough) into your sleeve, and wash the area or clothing as soon as possible.

When cases of the disease were increasing, people were advised to wear clean and suitable masks when they left home in order to reduce the risk of infection. This recommendation has changed in some areas. Many people where I live still wear masks in stores and other buildings, but the ones who don't are increasing,

Another important action is to try to work at home when you're sick instead of going to your workplace. This is especially important with respect to COVID-19, since the virus that causes the disease is so infectious. If it's impossible to work at home, social distancing should be maintained at work whenever possible. The recommended separation distance from other people (except those that we live with) is six feet. Vaccination against the disease should be investigated and considered.

Tissues are helpful for preventing the spread of infections.

Tissues are helpful for preventing the spread of infections.

An authoritative health agency should be consulted with respect to preventing or dealing with the SARS-CoV-2 virus. The virus is changing, and so are the recommendations by health agencies as they try to keep up with the changes.

The Use of Masks for the COVID-19 Infection

Specialized medical masks have been in short supply and are needed by health professionals treating coronavirus patients. In the recent past, the CDC said that it was important that other people wear less-specialized but still effective masks during the disease outbreak in order to leave the medical masks for doctors and nurses. They then changed this recommendation to recommend medical masks for some people as the situation worsened.

Thankfully, the COVID-19 situation is currently improving and the CDC's mask recommendations have changed, as the relevant link below describes. The organization now recognizes that masks are optional for some people in the United States but advisable for others.

If you are required or want to wear a mask, it would be good to investigate the latest news about them. Make sure that you look at reliable sources giving information about their type, construction, correct fit, and potential benefits.

Medical sources say that we shouldn't become overconfident if we wear a mask. Social distancing may still be important to help prevent the spread of disease. It's also important to handle a potentially contaminated mask carefully once we want to remove it. This topic is something else to investigate.

Moderate and regular exercise boosts the activity of the immune system and can be fun as well.

Moderate and regular exercise boosts the activity of the immune system and can be fun as well.

Maintaining a Healthy Immune System

While it's important to follow steps to reduce the chance of catching a virus, the steps aren't foolproof. Therefore, it's a good idea to keep the immune system functioning well. If the immune system is strong, it will be able to destroy many viruses.

A healthy lifestyle boosts immunity. A good diet that emphasizes a wide variety of whole, unprocessed foods and is low in sugar should be very helpful for improving and maintaining immunity. Moderate and regular exercise has been shown to boost the immune system, while smoking weakens it. Getting adequate sleep and taking steps to relieve stress can also help the immune system to function efficiently.

Although following a healthy lifestyle isn't a guarantee that we won't get sick, it can improve the odds. It also increases the chance that any infection that we experience will be mild instead of serious. Since another of its benefits is to reduce the chance of other diseases besides infections, it's a good idea to follow a healthy lifestyle whenever possible.


This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2013 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on November 07, 2013:

Thank you very much for the comment, Crafty!

CraftytotheCore on November 07, 2013:

Amazing Hub loaded with informational and educational facts. I didn't know about all of this info. Well presented.

Linda Crampton (author) from British Columbia, Canada on September 19, 2013:

Thank you very much for the comment and the votes, DDE.

Devika Primić from Dubrovnik, Croatia on September 19, 2013:

The Coronavirus - Infection and Disease Prevention interesting never heard of this virus but you have done a great job in writing out this information. Voted up and useful

Linda Crampton (author) from British Columbia, Canada on July 26, 2013:

That's a horrible thought, Deb! I certainly hope it's not true. Viruses do have the natural ability to pick up genes from another source and to undergo mutations (changes in gene structure), which are likely the reasons for them changing rapidly.

Deb Hirt from Stillwater, OK on July 26, 2013:

These odd diseases that are coming about now make me wonder if someone isn't experimenting with germ warfare...what say you?

Linda Crampton (author) from British Columbia, Canada on July 25, 2013:

Thanks, drbj. As always, I appreciate your visit and comment!

drbj and sherry from south Florida on July 25, 2013:

Another information-filled article with fascinating viral details. Thank you, Alicia. Your graphics are excellent.

Linda Crampton (author) from British Columbia, Canada on July 25, 2013:

Thank you very much, mperrottet. Viruses are fascinating, even though they can be dangerous or annoying! I appreciate all the votes and the share.

Margaret Perrottet from San Antonio, FL on July 25, 2013:

Excellent information. It would be wonderful if they could come up with a way to prevent viral infections in the future. I've always found the way that they reproduce fascinating and a little bit weird. Voted up, useful, interesting, awesome and sharing.

Linda Crampton (author) from British Columbia, Canada on July 24, 2013:

I'm sorry that your brother-in-law is having such a bad problem, Pamela, especially as it was caused by a diagnostic test which was supposed to help him, not hurt him! Thank you very much for the kind comment and for the share.

Pamela Oglesby from Sunny Florida on July 24, 2013:

Alicia, This is a very important hub as there are so many new viruses and bacteria in the world. My brothert-in-law has had two picc lines and IV antibiotics for several weeks for an infection that he received from getting a prostate biopsy. We need to follow all your suggestions and think twice about getting any procedures. It is a scary world anymore. This is an outstanding hub and I am sharing it also.

Linda Crampton (author) from British Columbia, Canada on July 24, 2013:

Thank you very much for the comment, vote and share, Bill. Yes, we may hear a lot about the MERS coronavirus soon, although I hope that's not the case!

Bill De Giulio from Massachusetts on July 24, 2013:

Hi Linda. How interesting. I also have not heard of the Coronavirus, yet. Sounds like it might be something we hear more about in the coming months. Once again, you amaze me with your medical knowledge. Thank you for the education. Voted up, shared, etc...

Linda Crampton (author) from British Columbia, Canada on July 24, 2013:

Thank you for the vote and the share, Tom. I appreciate your visit and comment!

Thomas Silvia from Massachusetts on July 24, 2013:

Hi my friend, not heard of this before but thanks for all the great information and prevention has well .

Vote up and more !!! Sharing !

Linda Crampton (author) from British Columbia, Canada on July 23, 2013:

90% on the poll is excellent, Faith! Yes, public restrooms can be a big problem when we're trying to avoid germs. Thank you very much for the comment, as well as for the vote and the share!

Faith Reaper from southern USA on July 23, 2013:

Hi AliciaC,

Thanks for the very insightful hub here full of useful information as to this specific virus, which I have not hear of until now. I did know 9 out of the 10 preventions. The one I never thought of is keeping the lid on the toilet seat down to prevent spraying, which makes a lot of sense, and there are not lids in public restrooms!

Excellent write.

Voted up +++ and sharing

Blessings, Faith Reaper

Linda Crampton (author) from British Columbia, Canada on July 23, 2013:

Hi, Bill. Coronaviruses may become more well known in the near future. The future of the MERS situation is uncertain at the moment. It may become a widespread problem or it may fizzle out quickly. Time will tell! Thanks for the comment.

Linda Crampton (author) from British Columbia, Canada on July 23, 2013:

Hi, Audrey. Thank you very much for the comment, all the votes and the share! Viruses are certainly pesky "creatures". It's frustrating when we take precautions and still get sick. I do find that when I follow the safety rules I'm able to avoid some infections that are travelling around the community, but not all of them. The infections may have been worse if I hadn't been trying to protect myself, but there's no way to know this!

Bill Holland from Olympia, WA on July 23, 2013:

Never heard of it, but thanks to you I am once again armed with valuable information. Thanks for keeping it simple enough for me to understand.

Audrey Hunt from Pahrump NV on July 23, 2013:

Thank you Alicia for putting the word out and writing such an informative hub. It seems that no matter how careful I am with germ prevention I still get sick at least once each year. I eat a healthy diet and get exercise regularly but still ""get the bug."

Great and useful stuff and voted up, UAI and sharing,