Coronavirus Disease 2019 (COVID-19): Overview

Coronavirus disease 2019 (COVID-19) is an illness that infects the lungs. It's caused by a type of coronavirus called SARS-CoV-2. There are many types of coronaviruses. They are a very common cause of colds and bronchitis. They can cause a lung infection called pneumonia. Symptoms can range from mild to severe. Some people have no symptoms. These viruses are also found in some animals.

The virus that causes COVID-19 changes (mutates) all the time. This is what all viruses do. It leads to different versions of a virus. These are called variants. COVID-19 variants may spread more easily from person to person. They may cause milder symptoms. Or they may cause more severe symptoms. 

The virus spreads and infects people easily. It can infect a person more easily if they are not immune to it. The virus most often spreads through droplets of fluid that a person coughs or sneezes into the air. It may be spread to you if you touch a surface with the virus on it and then touch your eyes, nose, or mouth.

Woman washing hands at kitchen sink.
To help prevent spreading the infection, wash your hands often, or use an alcohol-based hand sanitizer.

For the latest information from the CDC:

  • Go to the CDC website

  • Call 800-CDC-INFO (800-232-4636)

What are the symptoms of COVID-19?

Some people have no symptoms. Some have mild symptoms. And other people may have severe symptoms. Types of symptoms can vary from person to person. They may appear 2 to 14 days after contact with the virus. They can include:

  • Fever

  • Chills

  • Coughing

  • Trouble breathing or feeling short of breath

  • Sore throat

  • Stuffy or runny nose

  • Headache

  • Body aches

  • Tiredness

  • Nausea, vomiting, diarrhea, or abdominal pain

  • New loss of sense of smell or taste

Check your symptoms with the CDC’s Coronavirus Self-Checker.

What are possible complications of COVID-19?

The virus can cause an infection in the lungs. This is called pneumonia. In some cases, this can lead to death. Experts are still learning more about COVID-19 complications. Many other complications are possible. They include:

  • Low blood pressure

  • Kidney failure

  • Inflammation of the brain or heart

  • Rashes

Some people are at higher risk for complications. This includes:

  • Older adults

  • People with heart or lung disease

  • People with diabetes or kidney disease

  • People with health conditions that suppress the immune system

  • People who take medicines that suppress the immune system

Rarely, a child may have a severe complication. This is called multisystem inflammatory syndrome in children (MIS-C). MIS-C seems to be like Kawasaki disease. This is a rare illness. It causes inflammation of blood vessels and body organs. MIS can also happen in adults. But this is less common.  

How is COVID-19 diagnosed?

Your healthcare provider will ask:

  • What symptoms you have

  • Where you live

  • If you’ve traveled recently

  • If you’ve had contact with sick people

  • If you are vaccinated against COVID-19

  • If you have had COVID-19

 You may have 1 of these tests for COVID-19:

  • Viral (molecular) test. You may also hear this called a PCR or RT-PCR test. Viral tests are very accurate. A viral test looks for the genetic material (RNA) of the SARS-CoV-2 virus. There are a few ways to do this. A swab may be wiped inside your nose or throat. Or a long swab may be put into your nose down to the back of your throat. Or a sample of your saliva may be taken. Your test results may be back in 45 minutes to a few hours. This depends on the type of test. Some tests must be sent to a lab. These can take several days for the results. Test kits you can use at home are now available. Some of these need a prescription. If you use a home kit, follow the instructions in the kit closely. Some kits show results quickly at home. Others must be sent to a lab for the results.

  • Antigen test. This can find proteins from the SARS-CoV-2 virus. A swab may be wiped inside your nose or throat. Or a long swab may be put into your nose down to the back of your throat. Some results are back within 15 to 60 minutes. This depends on the type of test. Positive results are very accurate. But false positive results can happen. And the results can be negative even in people with COVID-19. This is more common in places where not many people have the virus. Antigen tests are more likely to miss a COVID-19 infection than a viral (molecular) test. You may need to have a viral test if your antigen test is negative but you have symptoms of COVID-19.

If your provider thinks or confirms that you have COVID-19, you may have other tests. These tests may include:

  • Antibody blood test. This type of test can show if you had the virus in the past. It shows antibodies for the virus in the blood. The accuracy of these tests varies. And they are not available everywhere. An antibody test may not show if you have an infection right now. This is because it can take up to a few weeks for your body to make antibodies. None of the antibody tests can yet be used to tell if a person is immune to the virus.

  • Sputum culture. If you have a wet cough, you may be asked to cough up a bit of mucus (sputum) from your lungs. This is tested for the virus. It may be tested for pneumonia.

  • Imaging tests. You may have a chest X-ray or CT scan.

Can you get COVID-19 again?

Yes, you can get COVID-19 more than once. You may have not gotten immunity. You could have lost the immunity. Or you may get COVID-19 from a different strain (variant) of the virus that you are not immune to. But the COVID-19 vaccine helps people who had COVID-19 lower their risk of having the illness again.

Vaccines for COVID-19

The FDA and CDC advise vaccines to help prevent COVID-19. The vaccines can also make the illness less severe. It can keep you from needing to go to the hospital.  And it can prevent the spread of the virus to other people. No vaccine is 100% effective at preventing an illness. But getting a vaccine is important. The Pfizer vaccine is available for people as young as age 5. Pregnant or breastfeeding people can have the vaccine. Ask your healthcare provider which vaccine may be best for you.

The vaccines are given as a shot (injection). This is most often done in a muscle in the upper arm. There is a 1-dose vaccine. This is from Johnson & Johnson. There are 2-dose vaccines. These are from Pfizer and Moderna. For a 2-dose vaccine, the second dose is given several weeks after the first. Some people may need a third dose of Pfizer or Moderna.

Who needs a third dose of Pfizer or Moderna?

A third dose of the Pfizer or Moderna vaccine may be needed for some people. This is for people who have a very weak immune system. The third dose is part of their first (primary) series. It's not a booster. This can happen if you had a solid organ transplant. It can be caused by other conditions or treatments. This third dose is to help a person with a weak immune system build up better protection against the virus. It's given at least 28 days after the second dose. Talk with your healthcare provider about your health risks to see if you need a third dose as part of your primary series.

COVID-19 vaccine booster shots

Everyone age 18 or older can get a COVID-19 booster shot. Here are your options.

Pfizer or Moderna booster

A booster shot of the Pfizer or Moderna vaccines is advised for many people. The booster shot is to be given at least 6 months after your primary series. Talk with your healthcare provider about your situation and risk. The CDC says these people should get a Pfizer or Moderna booster shot:

  • People age 50 or older

  • People age 18 or older who live in long-term care facilities

The CDC states people 18 to 49 may choose to get the booster. This depends on their specific case and risk. This includes people with certain health conditions. It also includes people whose job or living setting puts them at higher risk for COVID-19.

Johnson & Johnson booster

A booster shot of the 1-dose Johnson & Johnson vaccine is also available. It's advised for people ages 18 and older who got their first dose 2 or more months ago.

Mix and match

You may be able to choose which vaccine you get as a booster. This is called mix and match. Talk with your healthcare provider to learn more.

How is COVID-19 treated?

The most proven treatments right now are those to help your body while it fights the virus. This is known as supportive care. It includes:

  • Getting rest.This helps your body fight the illness.

  • Drinking fluids. Try to drink 6 to 8 glasses of fluids every day. Ask your provider which drinks are best for you. Don't have drinks with caffeine or alcohol.

  • Taking over-the-counter (OTC) medicine. These are used to help ease pain and reduce fever. Ask your provider which OTC medicine is safe for you to use.

You may need to stay in the hospital for severe illness. Your care may include:

  • IV (intravenous) fluids. These are given through a vein. This helps to replace fluids in your body.

  • Oxygen. You may be given supplemental oxygen. Or you may be put on a breathing machine (ventilator). This is done so you get enough oxygen in your body.

  • Prone positioning. Your healthcare team may regularly turn you on your stomach. This is called prone positioning. It helps increase the amount of oxygen you get to your lungs. Follow their instructions on position changes while you're in the hospital. Also follow their advice on the best positions to help your breathing once you go home.

  • Remdesivir. This is an antiviral medicine. The FDA has approved it for use on COVID-19. It works by stopping the spread of the SARS-CoV-2 virus in the body. It's approved only for people who are in the hospital. It's for people 12 years and older who weigh at least 88 pounds (40 kgs). In some cases, it may also be used for people younger than 12 years or who weigh less than 88 pounds (40 kgs).

  • Steroids or other anti-inflammatory medicines. These are used to lessen the intense inflammation that some people with COVID-19 can have. The inflammation can lead to more trouble breathing. It can cause other complications or death.

  • COVID-19 convalescent plasma. Plasma is the liquid part of blood. People who had COVID-19 may be asked to donate plasma. This is called COVID-19 convalescent plasma. The plasma may have antibodies. These can help fight COVID-19 in people who are very ill with it. The FDA has approved it for emergency use in some people with severe but early COVID-19. Ask your provider if you qualify to donate.

  • Monoclonal antibody therapy. The FDA approved this for emergency use in some people. They must have a positive COVID-19 viral test. They must have mild to moderate symptoms. They can’t be in the hospital. It's approved for people 12 years and older. They must weigh at least 88 pounds (40 kgs). And they must be at high risk for severe COVID-19 and a hospital stay. This includes people who are 65 years and older. And it includes people with some chronic conditions. This therapy is not approved for people who are in the hospital with COVID-19 or who need oxygen. Your healthcare team will tell you if you qualify.

Are you at risk for COVID-19?

You are at risk for COVID-19 if any of these apply to you:

  • You live in an area with cases of COVID-19

  • You traveled to an area with cases of COVID-19

  • You had close contact with someone who had COVID-19

Close contact means being within 6 feet.

Keep in mind that COVID-19 may be spread by people who do not show symptoms.

Last updated: 11/22/2021

Online Medical Reviewer: Barry Zingman MD
Online Medical Reviewer: L Renee Watson MSN RN
Date Last Reviewed: 9/1/2021
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