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Coronavirus disease 2019 (COVID-19)

Coronavirus - 2019; Coronavirus - novel 2019; 2019 Novel coronavirus; SARS-CoV-2

Coronavirus disease 2019 (COVID-19) is a viral respiratory illness that causes fever, coughing, and shortness of breath, but many other symptoms can occur. COVID-19 is caused by a highly infectious virus, and it has spread throughout the world. Most people get mild to moderate illness. Older adults and people with certain health conditions are at high risk for severe illness and death.


Respiratory system
Upper respiratory tract
Lower respiratory tract
Face masks prevent the spread of COVID-19
How to wear a face mask to prevent the spread of COVID-19
COVID-19 vaccine

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COVID-19 is caused by the SARS-CoV-2 virus (severe acute respiratory syndrome coronavirus 2). Coronaviruses are a family of viruses that can affect people and animals. They can cause mild to moderate respiratory illnesses, such as the common cold. Some coronaviruses can cause severe illness that can lead to pneumonia and even death.

COVID-19 most readily spreads to people within close contact (about 6 feet or 2 meters). When someone with the illness coughs, sneezes, sings, talks, or breathes, droplets and very small particles spray into the air. You can catch the illness if you breathe in these droplets or particles or they get in your eyes.

In some instances, COVID-19 may spread through the air and infect people who are more than 6 feet away. Small droplets and particles can remain in the air for minutes to hours. This is called airborne transmission, and it occurs especially in enclosed spaces with poor ventilation. However, it is more common for COVID-19 to spread through close contact.

Less often, the illness can spread if you touch a surface with the virus on it, and then touch your eyes, nose, mouth, or face. But this is thought to be a much less common way in which the virus spreads.

COVID-19 can spread from person to person quickly. As the virus spreads, it can change, and new variants will occur. Taking steps to slow the spread of the virus, such as by getting a COVID-19 vaccine, can help slow the development of new variants.

The United States Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) consider COVID-19 a serious public health threat globally and in the United States. The situation continues to evolve, and local rates of infection vary significantly, so it's important to follow current local guidance on how to protect yourself and others from getting and spreading COVID-19.


COVID-19 symptoms range from mild to severe. Older people and people with certain existing health conditions have a higher risk of developing severe illness and death. Health conditions that increase this risk include:

Symptoms of COVID-19 may include:

(Note: This is not a complete list of possible symptoms. More may be added as health experts learn more about the disease.)

Some people may have no symptoms at all. Many people have some, but not all of the symptoms.

Symptoms may appear within 2 to 14 days after being exposed. Most often, symptoms appear around 5 days after exposure. However, you can spread the virus even when you do not have symptoms.

More severe symptoms that require seeking medical help right away include:

Exams and Tests

If you have symptoms of COVID-19, your health care provider may decide to test you for the disease.

If you get tested for COVID-19, swabs from the back of the nose, the front of the nose, or the throat will be collected. If a person is thought to have COVID-19, these samples will be tested for SARS-CoV-2.


If you are recovering at home, supportive care is given to help relieve symptoms. People with severe illness will be treated in the hospital. Some people are being given experimental medicines.

The types of medicines given may vary depending upon how sick you are, your risk factors for serious illness from the disease, your age, and possibly what variant of the virus is causing the infection.

If you test positive for COVID-19, your provider may recommend antiviral drugs or another type of medicine called monoclonal antibodies.

If given soon after you become infected (5 to 7 days, depending on the drug), these medicines help your immune system fight off the virus. They may be given to adults and children with mild to moderate illness who are not hospitalized. These medicines include:

If you are being cared for in the hospital and are receiving oxygen therapy, treatment for COVID-19 may include the following medicines:

Other possible treatments are being studied, such as newer drugs and plasma from people who had COVID-19 and have recovered, but there is not enough evidence to recommend them at this time.

Based on available evidence, current treatment guidelines from the National Institutes of Health recommend against using some drugs for COVID-19, including chloroquine, hydroxychloroquine, and ivermectin. Do not take any drugs to treat COVID-19 except those prescribed by your provider. Check with your provider before treating yourself or a loved one with vitamins, nutrients, or any medicines prescribed in the past for other health problems. Since some COVID-19 medicines have interactions with other medicines or supplements you may be taking, always check with your provider before starting them.

Treatments for COVID-19 continue to be evaluated and guidelines continue to evolve. For the latest information about treatment for COVID-19, please see Coronavirus disease 2019 (COVID-19) treatment guidelines from the National Institutes of Health.

Possible Complications

Complications can include:

When to Contact a Medical Professional

You should contact your provider:

Call 911 or the local emergency number if you have:

Before you go to a doctor's office or hospital emergency department (ED), call ahead and tell them that you have or think you may have COVID-19. Tell them about any underlying conditions you might have, such as heart disease, diabetes, or lung disease. Wear the most protective mask you can that fits well without gaps and that you will wear, unless it makes it too hard to breathe. This will help protect other people you come in contact with.


COVID-19 vaccines are used to boost the body's immune system and protect against COVID-19. These vaccines are the best tool to help stop the COVID-19 pandemic. Adults and children ages 6 months and older can get the COVID-19 vaccine to protect themselves from the virus.

To find out where to get a vaccine in your area, check with your local public health department. You can also use the CDC VaccineFinder.

Once you are fully vaccinated, take these steps to continue to protect you and the people around you:

You might choose to wear a mask regardless of the level of transmission if:

If you have COVID-19 or have symptoms of it, you must isolate yourself at home and avoid contact with other people, both inside and outside your home, to avoid spreading the illness. This is called home isolation. You should do this immediately and not wait for any COVID-19 testing.

You should remain at home, avoid contact with people, and follow the guidance of your provider and local health department about when to stop home isolation. Follow the advice of your provider and local health department regarding when you may return to work or other activities.

It's also important to help prevent the spread of the disease to protect people at high risk of serious illness and to protect providers who are at the front lines of dealing with COVID-19.

To find out what it happening in your community, check your local or state government website.

Learn more about COVID-19 and you:

For the latest research information:

Information about COVID-19 from the World Health Organization:

Related Information



Centers for Disease Control and Prevention website. COVID-19 vaccines for children and teens. Updated July 21, 2022. Accessed August 15, 2022.

Centers for Disease Control and Prevention website. COVID-19: How to protect yourself and others. Updated August 11, 2022. Accessed August 15, 2022.

Centers for Disease Control and Prevention website. COVID-19: Frequently asked questions about COVID-19 vaccination. Updated July 20, 2022. Accessed August 15, 2022.

Centers for Disease Control and Prevention website. COVID-19: Long COVID or Post-COVID conditions. Updated December 16, 2022. Accessed January 6, 2023.

Centers for Disease Control and Prevention website. COVID-19: COVID-19 treatments and medications. Updated August 5, 2022. Accessed August 15, 2022.

Centers for Disease Control and Prevention website. COVID-19: What to do if you are sick. Updated March 22, 2022. Accessed August 15, 2022.

Centers for Disease Control and Prevention website. What you need to know about variants. Updated April 26, 2022. Accessed August 15, 2022.

National Institutes of Health. COVID-19 treatment guidelines. Clinical management of adults summary. Updated August 8, 2022. Accessed August 15, 2022.


Review Date: 8/5/2022  

Reviewed By: Frank D. Brodkey, MD, FCCM, Associate Professor, Section of Pulmonary and Critical Care Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 01/06/2023.

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