Medically Reviewed By William C. Lloyd III, MD, FACS

What is a coronavirus?

In today’s world, the term “coronavirus” has become interchangeable with COVID-19. However, this isn’t entirely accurate. Coronavirus is actually the name for a large group of viruses that scientists first described in the 1960s. COVID-19 is an acronym for one type of coronavirus infection, COronaVIrus Disease 2019. Coronaviruses get their name from the crown-like spikes on their surface. Corona is Latin for crown.

There are hundreds of types of coronavirus pathogens. Scientists divide them into four groups—alpha, beta, gamma and delta. Most of them move and spread among animal hosts, including bats, cats, camels, cattle, chickens and pigs. Two groups, alpha and beta, can infect humans. Currently, there are seven human coronaviruses. The most common ones that circulate throughout the world are:

  • 229E (alpha coronavirus)
  • NL63 (alpha coronavirus)
  • OC43 (beta coronavirus)
  • HKU1 (beta coronavirus)

Sometimes, animal coronavirus strains undergo changes—or mutations—that allow them to jump to humans. Although this is rare, the human immune system isn’t always able to effectively deal with the new virus when it happens. There have been three coronaviruses that have transitioned from an animal reservoir to humans in the last 20 years:

  • SARS-CoV (beta coronavirus causing Severe Acute Respiratory Syndrome in 2003)
  • SARS-CoV-2 (beta coronavirus causing COVID-19 in 2019)

Coronavirus infections cause respiratory disease in humans. The common ones (229E, NL63, OC43, HKU1) usually cause mild to moderate symptoms that resemble a cold. However, they can cause more serious disease, such as bronchitis and pneumonia in high-risk people. The newer coronaviruses (MERS, SARS, COVID-19) cause severe symptoms more often, although some people experience mild disease with COVID-19.

The newer strains also have the potential to be deadly. With MERS, 30 to 40% of infected people died from the disease. The death rate from SARS was around 10%. While these two pandemics have essentially burned out, COVID-19 is still ongoing. COVID-19 appears to be more contagious—meaning it spreads easier—than MERS and SARS, but is less deadly. Less than 2% of all reported COVID-19 infections in the United States have been fatal; however, it appears that many more people have been infected yet never developed any symptoms whatsoever. This case-mortality rate has gone down significantly since the outbreak began. It will likely continue to decline as the number of milder cases increases.

Anyone can catch a coronavirus infection. For healthy people, the infection isn’t likely to be serious. However, older people and those with chronic medical conditions have a higher risk of more severe disease. With COVID-19, the risk of death also increases with older age and underlying conditions.

Some targeted therapies have been approved for emergency use in high-risk patients with mild COVID-19. Other treatment options depend on the severity of the symptoms and are aimed at relieving them. When people develop cold-like symptoms, they may not even realize they have a coronavirus infection. Managing the infection is like treating any other cold. It includes rest, fluids, and over-the-counter (OTC) medicines to relieve cough and other symptoms. Contact your doctor if you are concerned about cold symptoms or if they persist.

With severe symptoms, hospitalization may be necessary to recover safely. Since the onset of the pandemic clinicians have learned many valuable lessons on how best to treat severe COVID-19 illness. Seek immediate medical care (call 911) for potentially serious symptoms including:

  • Bluish face, lips, nails or skin
  • Chest pain or pressure
  • Confusion or extreme sleepiness or fatigue
  • High fever

What are the symptoms of coronavirus infection?

Coronavirus infection symptoms vary in severity and mainly affect the respiratory tract. The common coronaviruses (229E, NL63, OC43, HKU1) usually cause mild to moderate upper respiratory symptoms of the common cold. Many people with COVID-19 also have this type of mild to moderate disease. However, all coronaviruses can cause severe symptoms in someone who is high risk due to age or poor health.

Common symptoms of coronavirus

Common coronavirus infection symptoms include:

  • Cough
  • Fever

Serious symptoms that might indicate a life-threatening condition

In some cases, coronavirus infections can be serious and even life threatening. Seek immediate medical care (call 911) if you, or someone you are with, have any of these serious symptoms including:

  • Blue discoloration of the face, lips, nails or skin
  • Chest pain or pressure, which may get worse with deep breathing or coughing

If cold symptoms seem to be worsening, see your doctor promptly. People at high risk of complications from coronavirus infections can deteriorate quickly.

What causes coronavirus infections and diseases?

Viruses belonging to the alpha and beta subgroups of the coronavirus family cause disease in humans. Currently, there are seven such viruses:

  • 229E
  • NL63
  • OC43
  • HKU1
  • MERS
  • SARS
  • COVID-19

There are hundreds of other coronaviruses, but they circulate among animals. In rare cases, coronaviruses in an animal reservoir mutate and infect humans. So far, only three (MERS, SARS, COVID-19) have done this. However, the possibility exists of other coronaviruses making the jump to human hosts.

What are the risk factors for coronavirus infection and disease?

Everyone is at risk of contracting a coronavirus infection. The common ones (229E, NL63, OC43, HKU1) spread easily and cause the common cold. However, there are a number of factors that increase the risk of developing a severe coronavirus infection. Risk factors include:

  • Advanced age. Severe disease risk increases with age; older adults are at greatest risk.

Reducing your risk of coronavirus

Coronavirus infection prevention involves basic personal hygiene. You may be able to lower your risk of coronavirus infection by:

  • Cleaning frequently touched objects and surfaces often with cleaners that will kill bacteria and viruses
  • Covering your nose and mouth with a tissue when you cough or sneeze and disposing of it right away. If you don’t have a tissue, use the corner of your elbow.
  • Keeping at least six feet between you and someone who is visibly sick
  • Avoiding indoor public spaces that are crowded and/or have poor ventilation
  • Not touching your eyes, nose or mouth
  • Staying home if you don’t feel well
  • Washing your hands often with warm, soapy water for 20 seconds at a time, especially before eating or touching your face. An alcohol-based hand sanitizer is a good alternative if soap and water are not available.

To slow the spread of the newer coronaviruses, including COVID-19, the CDC (Centers for Disease Control and Prevention) recommends wearing a face covering. Medical masks and other face coverings serve to protect others should you be carrying a coronavirus. They do this by providing a barrier to respiratory droplets from your mouth and nose. They can also protect the person wearing the mask because they can filter out small particles that may contain viruses.

How is coronavirus disease treated?

Coronavirus treatment is focuses on relieving symptoms and preventing complications. Most people recover on their own with home treatment including:

  • Drinking plenty of fluids
  • Getting lots of rest
  • Remaining at home while you are sick
  • Sitting in a hot shower or using a humidifier to loosen and relieve a cough
  • Taking over-the-counter (OTC) medicines to help control cough, reduce fever, and ease other symptoms

Talk with your doctor or pharmacist about the best OTC medicines for you, based on your symptoms and medical history.

People who develop a mild-to-moderate case of COVID-19 and who are at high risk of more severe disease may be candidates for monoclonal antibody drugs that target a SARS-CoV-2 protein. These drugs have emergency use authorization because clinical trials show they can reduce emergency room visits and hospitalizations.

People with severe symptoms may require treatment in a hospital to recover safely. Treatment still focuses on relieving symptoms and staff will monitor closely for potential complications. They can also provide more supportive treatments, such as IV (intravenous fluids), steroids, biologics, and supplemental oxygen. There are many COVID-19 drugs in clinical trials, and some have emergency use authorization. If you or a loved one is hospitalized for COVID-19, ask the doctor about clinical trial drugs.

What are the potential complications of a coronavirus infection?

Most coronavirus infections result in mild to moderate disease. This is true even for the novel COVID-19 coronavirus. However, severe disease is possible, particularly for the elderly and those with underlying medical conditions.

The common coronaviruses (229E, NL63, OC43, HKU1) can cause bronchitis and pneumonia in these populations. COVID-19 can cause serious and potentially fatal respiratory distress and critical disease in high-risk groups. If you are at high risk of complications from a coronavirus infection, talk with your doctor about signs and symptoms that should prompt you to seek medical care.

Was this helpful?
  1. United States COVID-19 Cases and Deaths by State Updated August 28, 2020. Centers for Disease Control and Prevention.
  2. About MERS. Centers for Disease Control and Prevention.
  3. Coronavirus. Yale Medicine.
  4. Coronaviruses. National Foundation for Infectious Diseases.
  5. Coronaviruses. National Institute of Allergy and Infectious Diseases.
  6. Coronaviruses Have Been Around For Centuries: What Differentiates COVID-19? Cleveland Clinic.
  7. COVID-19: People at Increased Risk of Severe Disease, Older Adults.
  8. COVID-19, MERS and SARS. National Institute of Allergy and Infectious Diseases.
  9. Human Coronavirus Types. Centers for Disease Control and Prevention.
  10. Severe Acute Respiratory Syndrome (SARS). Centers for Disease Control and Prevention.
  11. Coronavirus (COVID-19) Update: FDA Authorizes Monoclonal Antibody for Treatment of COVID-19. Food and Drug Administration.
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Sep 10
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