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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. The virus is called SARS-CoV-2. There are many types of coronaviruses. They are a 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 types of viruses are also found in some animals.

Viruses change (mutate) all the time. The changes lead to different forms 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. In some cases, you can get it from touching a surface with the virus on it and then touching 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.

To learn more

For the latest 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. Others may have severe symptoms. This varies from person to person. Symptoms may start 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 belly 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. This can lead to death in some cases. Experts are still learning more about COVID-19 problems. Problems may include:

  • Low blood pressure

  • Kidney failure

  • Inflammation of the brain or heart

  • Rashes

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

  • Older adults

  • People with heart or lung disease

  • People with diabetes or kidney disease

  • People with health conditions that limit the immune system

  • People who take medicines that limit 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 swelling 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

Know your testing options with the CDC's COVID-19 Viral Testing Tool. 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. You can now get test kits to use at home. Some of these need a prescription. Follow the instructions in the kit closely if you use a home kit. 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. 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.

  • Breath test. This rapid test is not widely available at this time. It finds SARS-CoV-2 infection in the breath. The test is done at providers' offices, hospitals, and mobile testing sites.

You may have other tests if your provider thinks or confirms that you have COVID-19. 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 not have 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 lower the risk for COVID-19.

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 others. No vaccine is 100% effective at preventing an illness. But getting a vaccine is important. COVID-19 vaccines are available for people as young as 6 months old. Pregnant or breastfeeding people can have the vaccine. Vaccines are given as a primary series.Boosters are given later to help with protection.

The vaccines are given as a shot (injection) into the muscle. Ask your healthcare provider which vaccine is best for you and your family. There is a 1-dose vaccine from Johnson & Johnson (J&J) for people ages 18 and older. Or a 2-dose vaccine from Novavax for people ages 12 and older. Two-dose Pfizer and Moderna vaccines are for people as young as 6 months old. They are given in several doses a few weeks apart. People with a weak immune system may have other advice. Talk with your healthcare provider about which vaccine is best for you and your family.

COVID-19 vaccine booster shots

People age 5 or older can get a COVID-19 booster shot. It's given a few months after their primary series. Boosters can help with protection against COVID-19 that may have decreased over time.

Booster advice varies by vaccine, age, health, and COVID-19 variants. Talk with your provider about your risk and when to get a booster.

How is COVID-19 treated?

The best treatments right now are those to help your body while it fights the virus. This is called supportive care. It includes:

  • Rest.This helps your body fight the illness.

  • 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.

  • 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.

Talk with your provider if you have confirmed COVID-19. You may qualify for medicines approved by the FDA to prevent severe COVID-19 infection.

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

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

  • Oxygen. You may be given extra 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 and at home.

  • Antivirals and monoclonal antibodies. The FDA has approved certain antivirals and monoclonal antibodies to treat COVID-19. These treatments are for people who are more likely to get very sick. These treatments are not available for everyone. Talk with your healthcare provider to learn more.

    • Antivirals stop the SARS-CoV-2 virus from spreading in the body.

    • Monoclonal antibodies help the immune system fight the virus.


  • Steroids or other anti-inflammatory medicines. These are used to lessen the inflammation that some people with COVID-19 have. 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. Check with your provider to see if this is an option in your area.

Are you at risk for COVID-19?

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

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

  • You had close contact (within 6 feet) with someone who had COVID-19

COVID-19 may be spread by people who don't show symptoms.

Date last modified: 9/08/2022

Online Medical Reviewer: Barry Zingman MD
Online Medical Reviewer: L Renee Watson MSN RN
Date Last Reviewed: 9/1/2021
© 2000-2023 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.