Coronavirus Disease 2019 (COVID-19)

What is coronavirus disease 2019 (COVID-19)?

Coronavirus disease 2019 (COVID-19) is a respiratory illness. It's caused by a new (novel) coronavirus called SARS-CoV-2. There are many types of coronavirus. Coronaviruses are a very common cause of bronchitis. They may sometimes cause lung infection (pneumonia). Symptoms can range from mild to severe respiratory illness. These viruses are also found in some animals.

All 50 states in the U.S. have reported cases of COVID-19. Like other viruses, the virus that causes COVID-19 changes (mutates) all the time. This leads to variants such as the Delta variant. COVID-19 variants, including the Delta variant, have been found across the world, including in the U.S. COVID-19 variants may spread more easily from person to person. They may cause milder or more severe symptoms. COVID-19 is a rapidly-emerging infectious disease. This means that scientists are actively researching it.

There are information updates regularly. Visit the CDC website for the latest information. Or call 800-CDC-INFO (800-232-4636).

What causes coronavirus disease 2019 (COVID-19)?

Public health officials are working to find the source. How the virus spreads is not yet fully understood, but it seems to spread and infect people fairly easily. Some people who have been infected in an area may be unsure how or where they became infected. The virus may be spread through droplets of fluid that a person coughs or sneezes into the air. It may be spread if you touch a surface with virus on it, such as a handle or object, and then touch your eyes, nose, or mouth.

Who is at risk for coronavirus disease 2019 (COVID-19)?

You are at risk for infection if you’ve been to a place where people have been sick with this virus. You are at higher risk if you are not fully vaccinated and:

  • Recently traveled to or live in an area with a COVID-19 outbreak

  • Had contact with a person who was diagnosed with or who may have COVID-19

What are the symptoms of coronavirus disease 2019 (COVID-19)?

Symptoms can vary a lot from person to person. Some people have no symptoms (this is called asymptomatic). Some people have mild symptoms, and some people report feeling very sick. As experts learn more about COVID-19, other symptoms are being reported. Symptoms may appear 2 to 14 days after contact with the virus. Symptoms can include:

  • Fever or chills

  • Coughing

  • Trouble breathing

  • Sore throat

  • Stuffy or runny nose

  • Headache or body aches

  • Tiredness (fatigue)

  • Nausea, vomiting, diarrhea, or belly (abdominal) pain

  • New loss of sense of smell or taste

You can check your symptoms with the CDC’s Coronavirus Self-Checker.

How is coronavirus disease 2019 (COVID-19) diagnosed?

Your healthcare provider will look at the risk for COVID in your community and will ask about your symptoms. He or she will also ask about your recent travel and contact with sick people. If your healthcare provider thinks you may have the COVID-19 virus, he or she will work closely with your local health department to see if you should be tested. Follow all instructions from your healthcare provider. COVID-19 is diagnosed by:

  • Diagnostic test. Diagnostic tests tell if you have a current COVID-19 infection. There are two types of diagnostic tests:

    • Viral (molecular) test. You may also hear it called RT-PCR test. Viral tests are very accurate. A viral test looks for the SARS-CoV-2 virus's genetic material. A viral test can also detect COVID-19 variants. There are a few ways to do this. A nose-throat swab may be wiped inside your nose to the very back of your throat. Other tests are either done by nose or throat swab. Or a sample of your saliva may be taken. Availability of tests vary by location. Depending on the test, some results are back within about 30 minutes. Some tests must be sent to a lab and can take several days before the results are back. Home test kits are now available but vary by location. Some need a prescription. Some kits get results quickly at home. Others must be sent to a lab for the results.
    • Antigen test. This looks for proteins from the SARS-CoV-2 virus. This is done by a nose or a nose-throat swab. Depending on the test, some results are back within an hour. Positive results are highly accurate, but false positives can happen, especially in places where few people have the virus. Antigen tests are more likely to miss a COVID-19 infection than a viral (molecular) test. If your antigen test is negative but you have symptoms of COVID-19, your healthcare provider may order a viral test.

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

  • Antibody blood test. Antibody tests are being looked at to find out if a person has previously been infected with the virus and may now have antibodies in their blood to give some immunity. The accuracy and availability of antibody tests vary. An antibody test may not be able to show if you have a current infection because it can take up to a few weeks after infection to make antibodies. It's not yet known how long immunity lasts after being infected with the virus.

  • Sputum culture. A small sample of mucus coughed from your lungs (sputum) may be collected if you have a moist cough. It may be checked for the virus or to look for pneumonia.

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

Note about re-infection and immunity

At this time, it's unclear if people can be re-infected with COVID-19. The CDC notes that if a person has fully recovered from COVID-19 and is retested within 3 months of the first infection, they may continue to have low levels of the virus in their bodies and test positive for COVID-19, even though they are not spreading COVID-19. Having a positive COVID-19 test after an infection doesn't mean you can't be reinfected. It's not yet known how long immunity lasts after being infected with the virus

How is coronavirus disease 2019 (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. For serious COVID-19, you may need to stay in the hospital. Supportive care may include:

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

  • Staying hydrated. Drinking liquids is the best way to prevent dehydration. Try to drink 6 to 8 glasses of liquids every day, or as advised by your provider. Also check with your provider about which fluids are best for you. Don't drink fluids that contain caffeine or alcohol.

  • Taking over-the-counter (OTC) pain medicine. These are used to help ease pain and reduce fever. Follow your healthcare provider's instructions for which OTC medicine to use.

For severe illness, you may need to stay in the hospital. Care during severe illness may include:

  • IV (intravenous) fluids. These are given through a vein to help keep your body hydrated.

  • Oxygen. Supplemental oxygen or ventilation with a breathing machine (ventilator) may be given. This is done so you get enough oxygen in your body.

  • Prone positioning. Depending on how sick you are during your hospital stay, your healthcare team may turn you regularly on your stomach. This is called prone positioning. It's done to help increase the amount of oxygen you get to your lungs. Follow your healthcare team's instructions on position changes while you're in the hospital. Also follow their discharge advice on the best positions to help your breathing once you go home.

  • Remdesivir. The FDA has approved an IV (intravenous) antiviral medicine called remdesivir. It works by stopping the spread of the SARS-CoV-2 virus in the body. It's approved for people in the hospital with COVID-19. It's for people 12 years and older who weigh more than about 88 pounds (40 kgs). Remdesivir is approved only for people who need to be treated in the hospital. In certain cases, it may also be used for people younger than 12 years or who weigh less than about 88 pounds (40 kgs).

Research continues on other therapies that are still experimental. These include:

  • COVID-19 convalescent plasma. People who have had COVID-19 and are fully recovered may be asked by their healthcare team to consider donating plasma. This is called COVID-19 convalescent plasma donation. Plasma from people fully recovered from COVID-19 may contain antibodies to help fight COVID-19 in people who are currently seriously ill with the disease. Experts don't know if the donated plasma will work well as a treatment. Research continues, and the FDA has approved it for emergency use in certain people with serious or life-threatening COVID-19. Talk with your provider to learn more about convalescent plasma donation and whether you qualify to donate.
  • Monoclonal antibody therapy. The FDA recently approved this experimental therapy for emergency use for certain people who have a positive COVID-19 viral test and have mild to moderate symptoms but are not in the hospital. It's not widely available and is still being investigated. It's approved for people 12 years and older who weigh about 88 pounds (40 kgs) and are at high risk for severe COVID-19 and a hospital stay. This includes people who are 65 years or older and people with certain chronic conditions. Monoclonal antibody therapy is not approved for people who:
    • Are in the hospital with COVID-19, or
    • Need oxygen therapy for COVID-19, or
    • Need oxygen therapy for a chronic condition and need to have oxygen flow increased because of COVID-19.

What are possible complications of coronavirus disease 2019 (COVID-19)?

In many cases, this virus can cause infection (pneumonia) in both lungs. In some cases, this can cause death, especially in older adults and people who have serious health conditions such as heart or lung disease or diabetes.

As experts learn more about COVID-19, other complications are being reported that may be linked to COVID-19. Rarely, some children have developed severe complications called multisystem inflammatory syndrome in children (MIS-C). MIS-C seems to be similar to Kawaski disease, a rare condition causing inflammation of blood vessels and body organs. It's not yet known if MIS-C happens only in children, or if adults are also at risk. It's also not known if it's related to COVID-19 because many children, but not all, have tested positive for the virus. Experts continue to study MIS-C. The CDC advises healthcare providers to report to local health departments any person under age 21 years old who is ill enough to be in the hospital and has all of the following:

  • A fever over 100.4°F (38.0°C) for more than 24 hours and a positive SARS-CoV-2 test or exposure to the virus in the last 4 weeks

  • Inflammation in at least 2 organs such as the heart, lungs, or kidneys with lab tests that show inflammation

  • No other diagnoses besides COVID-19 explain the child's symptoms

What can I do to prevent coronavirus disease 2019 (COVID-19)?

The FDA has approved several vaccines to prevent COVID-19. One vaccine has been approved for people as young as 12. Talk with your healthcare provider about your risks and which vaccine may be best for you and your family.

Pregnant or breastfeeding people may choose to be vaccinated. Expert groups, including ACOG and the CDC, advise pregnant or breastfeeding people to talk with their healthcare provider about the vaccine.

The vaccines are being rolled out to the public in phases. Check your local health department for your community's roll-out plans. The vaccines are given as a shot (injection) in the arm muscle. A 1-dose or 2-dose vaccine may be given. If you get the 2-dose vaccine, the second dose is given several weeks after the first.

The best prevention is to have no contact with the virus. Follow safety advice such as social distancing, wearing masks, using good hand hygiene, and getting a COVID-19 vaccine when it's available to you.

CDC recommends not traveling until you are fully vaccinated against COVID-19. This is because travel raises your chance of getting and spreading the infection. Fully vaccinated means 2 weeks after getting either the 1-dose or the second shot of the 2-dose vaccine. Be aware of travel precautions, both within the U.S. and abroad. For the most current CDC travel advisories, visit the CDC website.

Prepare and protect yourself from COVID-19

  • Wash your hands often with soap and clean, running water for at least 20 seconds.

  • If you don’t have access to soap and water, use an alcohol-based hand sanitizer often. Make sure it has at least 60% alcohol.

  • Don't touch your eyes, nose, or mouth unless you have clean hands.

  • As much as possible, don't touch "high-touch" public surfaces such as doorknobs and handles, cabinet handles, and light switches. Don't shake hands.

  • Clean home and work surfaces often with disinfectant. This includes desk surfaces, printers, phones, kitchen counters, tables, fridge door handle, bathroom surfaces, and any soiled surface. Closely follow disinfectant label instructions. See the CDC’s cleaning website for detailed instructions.

  • Cough or sneeze into a tissue, then throw the tissue into the trash. If you don't have tissues, cough or sneeze into the bend of your elbow.

  • Stay informed about COVID-19 in your area. This is because instructions are changing regularly and vary by where you live. Follow local instructions about being in public. Be aware of events in your community that may be postponed or canceled, such as school and sporting events.

  • Wear a mask as advised. The CDC advises wearing a cloth face mask with several layers of washable, breathable fabric and a nose wire. Or you can wear a disposable paper mask with a cloth mask over it. Wear the mask so that it covers both your nose and mouth.

    • The CDC advises all people older than 2 who are not fully vaccinated to wear a mask and stay 6 feet away from others while in public.
    • The CDC advises people with weak immune systems, even if fully vaccinated, to continue wearing masks and to stay 6 feet away from others while in public.
    • If you are fully vaccinated, you can take part in many activities that you did before COVID-19. But be aware of safety precautions in your area. To protect against the Delta variant, the CDC advises all people over age 2, including those who are fully vaccinated, to wear a mask indoors in public if you are in an area of high numbers of COVID-19 cases. See the CDC's county data website for current transmission information in your area.

  • Stay away from people who are sick.

  • Check your home supplies. Consider keeping a 2-week supply of medicines, food, and other needed household items.

  • Make a plan for childcare, work, and ways to stay in touch with others. Know who will help you if you get sick.

  • Experts don't know if animals spread SARS-CoV-2. But it's always a good idea to wash your hands after touching any animals. Don't touch animals that may be sick.

  • Don’t share eating or drinking utensils with sick people.

  • Don’t kiss someone who is sick.

If you are sick with COVID-19 symptoms

  • Stay home. Call your healthcare provider and tell them you have symptoms of COVID-19. Do this before going to any hospital or clinic. Follow your provider's instructions about testing and staying home. You may be advised to isolate yourself at home. This is called self-isolation or self-quarantine.

  • Don’t panic. Keep in mind that other illnesses can cause similar symptoms.

  • Stay away from work, school, and public places. Limit physical contact with family members and pets. Don't kiss anyone or share eating or drinking utensils. Clean surfaces you touch with disinfectant. This is to help prevent the virus from spreading.

  • Cough or sneeze into a tissue, then throw the tissue into the trash. If you don't have tissues, cough or sneeze into the bend of your elbow.

  • Wear a face mask. This is to protect other people from your germs. If you are not able to wear a mask, your caregivers should when you are in the same room with them. Wear the mask so that it covers both the nose and mouth.

  • If you need to go in to a hospital or clinic, expect that the healthcare staff will wear protective equipment such as masks, gowns, gloves, and eye protection. You may be told to enter or stay in a separate area. This is to prevent the possible virus from spreading.

  • Tell the healthcare staff about recent travel. This includes local travel on public transport. Staff may need to find other people you have been in contact with. This is called contact tracing.

  • Follow all instructions the healthcare staff give you.

If you have been exposed to someone with COVID-19

  • If you are fully vaccinated, you don't need to stay home away from others (quarantine) if you have been exposed and don't have symptoms. You don't need to be tested for COVID-19 if you've been exposed and don't have symptoms. Stay informed of your community's instructions.
  • If you have never had COVID-19 and have not been fully vaccinated but are exposed , stay home and monitor your health. This is called quarantine. Limit contact with others. Don't go to work, school, or out in public. Keep watch for symptoms of the virus. Tell your provider right away if you have symptoms. Take your temperature every morning and evening for at least 14 days. This is to check for fever. Keep a record of the readings. Watch for other symptoms such as cough and shortness of breath.
  • If you have not been fully vaccinated but are exposed to COVID-19, you likely will be advised to quarantine to help prevent spread of COVID-19. Follow your provider's instructions about quarantine and testing. If you have not been fully vaccinated and have COVID-19 symptoms, the CDC recommends viral testing if you have had close contact with someone known to have COVID-19. Close contact means being within 6 feet of a person known to have COVID-19 for a total of 15 minutes or more. This could be multiple short encounters that add up to at least 15 minutes over a 24-hour period.

  • If you've had COVID-19 in the last 3 months but are fully recovered without symptoms and you have been exposed to someone with COVID-19, your restrictions are different. If you are symptom-free, you don't need to quarantine or be re-tested. The CDC doesn't recommend retesting unless you have symptoms of COVID-19 and your new symptoms can't be linked to another illness. Contact your healthcare provider if you have any questions. If you develop symptoms, stay home. If you had COVID-19 over 3 months ago and have been exposed again, treat it like you've never had COVID-19 and stay home, limit your contact with others, call your provider, and monitor for symptoms.

How to manage coronavirus disease 2019 (COVID-19)

If you've been diagnosed with COVID-19:

  • Stay home. Don’t leave your home unless you need to get medical care. Don't go to work, school, or public areas. Don't use public transportation or taxis.

  • Follow all instructions from your healthcare provider. Call your healthcare provider’s office before going. They can prepare and give you instructions. This will help prevent the virus from spreading.

  • Limit contact with other people in your home and don't have visitors in your house

  • Wear a face mask. This is to protect other people from your germs. If you are not able to wear a mask, your caregivers should when you are in the same room with them. Wear the mask so that it covers both the nose and mouth.

  • Don’t share household items or food.

  • Cover your face with a tissue when you cough or sneeze. Throw the tissue away. Then wash your hands.

  • Wash your hands often.

If you are caring for a sick person:

  • Follow all instructions from healthcare staff.

  • Wash your hands often.

  • Wear protective clothing as advised.

  • Make sure the sick person wears a mask. If they can't wear a mask, don't stay in the same room with the person. If you must be in the room, wear a face mask. Wear the mask so that it covers both the nose and mouth.

  • Keep track of the sick person’s symptoms.

  • Clean surfaces, fabrics, and laundry thoroughly.

  • Keep other people and pets away from the sick person.

When should I call my healthcare provider?

Call your healthcare provider:

  • If you’ve recently traveled or have been in an area with COVID-19 and have symptoms

  • If you have been diagnosed with COVID-19 and your symptoms are worse

Key points about coronavirus disease 2019 (COVID-19)

  • Coronavirus disease 2019 (COVID-19) is a respiratory illness.

  • It's caused by a new (novel) type of coronavirus called SARS-CoV-2. The virus may be spread through droplets of fluid that a person coughs or sneezes into the air. It may be spread if you touch a surface with virus on it, such as a handle or object, and then touch your eyes, nose, or mouth.

  • The best way to prevent COVID-19 is not to be exposed to the virus. Wash your hands often and stay informed about COVID-19 in your area. For the most current CDC guidance on safety precautions and travel, visit the CDC website.

  • Be aware of safety precautions in your area, including mask requirements. For the most current CDC guidance on masks, see the CDC's county data website.

  • The FDA has approved several vaccines to prevent COVID-19. One vaccine has been approved for people as young as 12. Pregnant or breastfeeding people may choose to be vaccinated after talking with their healthcare provider. The vaccines are given as a shot (injection) in the arm muscle. A 1-dose or 2-dose vaccine may be given. If you get the 2-dose vaccine, the second dose is given several weeks after the first.
  • Symptoms include fever, coughing, and trouble breathing. Some people report digestive upset, loss of appetite, runny nose, headache and body aches, chills or repeated shaking with chills, and new loss of taste and smell. In some cases, this virus can cause lung infection (pneumonia).

  • If you have COVID-19, treatment is done to help your body while it fights the virus. This is known as supportive care.

  • If you are or were in an area with COVID-19 and have a fever or other symptoms (even if you've been fully vaccinated), stay away from other people. Call your healthcare provider. Explain that you have been exposed to COVID-19 and have symptoms. Do this before going to any hospital or clinic so as not to spread an illness to others. Wait for instructions.

  • If your healthcare provider thinks you may have COVID-19, they will work closely with your local health department. Follow all instructions from your healthcare provider.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
  • Ask if your condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if you don't take the medicine or have the test or procedure.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.

Date last modified: 7/28/2021

Medical Reviewer: Arnold Lentnek MD
Medical Reviewer: Renee Watson RN
© 2000-2021 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.
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