Coronavirus ​Disease ​2019 ​(COVID-​19)​ | OSF HealthCare
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Coronavirus ​Disease ​2019 ​(COVID-​19)​

What is COVID-19?

Coronavirus disease 2019 (COVID-19) is an infectious disease that most often causes a respiratory illness. It's caused by a virus called SARS-CoV-2. There are many types of coronavirus. Coronaviruses are a 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.

Like other viruses, the virus that causes COVID-19 changes (mutates) all the time. This leads to variants that can easily spread, including the delta and omicron variants. They may cause milder or more severe symptoms.

COVID-19 information is updated regularly. Visit the CDC website for the latest information. Or call 800-CDC-INFO (800-232-4636).

What causes COVID-19?

The virus SARS-CoV-2 causes COVID-19. The original source of the virus is unknown. The virus infects people and spreads fairly easily. Some people who have been infected may be unsure how or where they became infected. The virus is most commonly spread through droplets of fluid that a person expels into the air by talking, coughing, singing, or sneezing. It some cases, it may be spread if you touch a surface with virus on it, such as a handle or object, or the skin of an infected person, and then touch your eyes, nose, or mouth.

Who is at risk for COVID-19?

You are at risk for infection if you’ve been in close contact with people who are actively infected or 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 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. 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

  • Rash

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

How is COVID-19 diagnosed?

Your healthcare provider will look at the risk for COVID-19 in your community and with your contacts and travel, and will ask about your symptoms. If your healthcare provider thinks you may have the COVID-19 virus, they will suggest testing for the virus. Know your testing options with the CDC's COVID-19 Viral Testing Tool . COVID-19 is diagnosed by:

  • Diagnostic test. Diagnostic tests tell if you have a current COVID-19 infection. There are 2 types of diagnostic tests:

    • Viral (molecular) test. You may also hear it called a PCR or RT-PCR test. Viral tests are very accurate. A viral test looks for the SARS-CoV-2 virus's genetic material. 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 throat swab, or sometimes by saliva. Depending on the test, some results are back in about 15 to 30 minutes. 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.

The FDA has authorized a COVID-19 breath test. It finds signs of a SARS-CoV-2 infection in the breath. The test is done at providers' offices, hospitals, and mobile testing sites. It's not widely available at this time.

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 can be done to find out if a person has recently been infected with the virus. 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. Current antibody tests can't tell whether you are immune from COVID-19 and are not approved to test for immunity.

  • 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

You can be re-infected with COVID-19 especially after being exposed to a new variant or if you did not develop immunity after vaccination or from a prior COVID episode. It's not yet known how long immunity may last after being infected with the virus or getting a COVID-19 vaccine.

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. If you have confirmed COVID-19, talk with your healthcare provider about your situation and risk. You may qualify for certain medicines authorized by the FDA to prevent severe COVID-19 infection. 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.

  • Antiviral medicines and monoclonal antibodies. The FDA has authorized antiviral medicines and monoclonal antibodies to treat mild to moderate COVID-19 in certain people who are more likely to get very sick. Talk with your healthcare provider to learn more.

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

    • Monoclonal antibodies help the immune system recognize and fight the virus.

  • Steroids and other anti-inflammatory medicines. These are used to treat the intense inflammation that can occur with COVID-19. This inflammation is a major cause of progressive respiratory symptoms, kidney failure and 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.

What are possible complications of COVID-19?

The virus can cause infection in the lungs or kidneys. It can also cause heart disease, brain and spinal symptoms, and other complications. 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. Many people have ongoing fatigue, shortness of breath, racing heart, loss of appetite or change of taste or smell after COVID-19, and these can persist for weeks or months.

Rarely, some children have developed severe complications called multisystem inflammatory syndrome in children (MIS-C). MIS-C seems to be similar to Kawasaki disease, a rare condition causing inflammation of blood vessels and body organs. MIS can also occur in adults, but less frequently 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 COVID-19?

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

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

Vaccines

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. Vaccines are given as a primary series and then as boosters to help with protection.

Pregnant or breastfeeding people are advised 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 given as a shot (injection) in the muscle. There is a 1-dose vaccine. This is from Johnson & Johnson (J&J). Or a 2-dose shot from Novavax. Both J&J and Novavax are for adults ages 18 and older. Pfizer and Moderna vaccines are available for people as young as 6 months old. They are given in several doses a few weeks apart, depending on age and overall health. People with a very weak immune system have different advice. Talk with your healthcare provider about which vaccine is best for you and your family.

When traveling, protect yourself by staying current with your COVID-19 vaccines Be aware of travel precautions, both within the U.S. and abroad. For the most current CDC travel advisories and how to protect yourself, visit the CDC travel website.

Booster shots

People age 5 or older can get a COVID-19 booster shot several months after completing their primary series. Boosters can help with protection against COVID-19 that may have decreased over time after getting the primary series. Pfizer and Moderna vaccine boosters are preferred.

Booster advice varies by vaccine, age, health status, and COVID-19 variants. Talk with your healthcare provider to learn more about your risk and when you and your family should get a booster.

Prepare and protect yourself from COVID-19

  • Wear a mask as advised. Choose a mask with the best fit, protection, and comfort for you. Know your community's COVID-19 Community Level.

  • You may choose to mask at any time. People with COVID-19 symptoms, a positive COVID-19 test, or exposure to someone with COVID-19 should wear a mask.

  • If you are in an area with a highCOVID-19 Community Level and are age 2 or older, wear a mask indoors in public, even if you are fully vaccinated.

  • If you are at risk for severe COVID-19, consider taking extra precautions such as wearing a mask in public even if your Community Level is medium.

  • 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.

  • 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

Information about quarantine and isolation is changing often. See the CDC's website for current, detailed information. Also, follow your local area's instructions on testing and staying home.

  • Stay home and isolate. Isolate when you are sick or when you test positive for the virus, even if you don't have symptoms. Call your healthcare provider and tell them you have symptoms of COVID-19. Do this before going to any hospital or clinic.

  • Stay away from work, school, and public places. Limit physical contact with family members and pets. Stay is a separate room or area with its own bathroom if available. 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 well-fitting face mask that covers your nose, mouth, and chin. 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.

  • If you need to go 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

You may be advised to stay at home in quarantine if you come into close contact with someone with COVID-19 and you may or may not have been infected. Quarantine is a way to prevent the spread of COVID-19 by keeping people who have been exposed to COVID-19 away from others.

Your risk of getting COVID-19 is much lower after exposure if you are fully vaccinated and boosted. You don't need to quarantine if you've been exposed but don't have symptoms, and:

  • You are fully vaccinated and have gotten booster shots.

  • You are 5 to 17 years old and have completed the initial vaccine series.

  • You had COVID-19 in the last 3 months confirmed by a positive viral test.

The date of your last exposure to COVID-19 is considered day 0, so day 1 is the day after your exposure. Get tested at least 5 days after being exposed and watch for symptoms. Wear a well-fitting mask around others for 10 days after exposure.

If you have been exposed and have symptoms (even if you've been fully vaccinated and have gotten a booster), get tested and stay home. If your test result is positive, isolate at home for 5 days (day 0 to day 5). If you don't have symptoms or your symptoms are getting better after 5 days, you can leave your house. Continue to wear a mask around others for 5 more days. If you have a symptoms or a fever, continue to stay home until your fever goes away.

If you are not fully vaccinated and boosted and have been exposed to someone with COVID-19:

Call your healthcare provider and follow all instructions. Stay home away from others and monitor your health. This is called quarantine. CDC advises that you quarantine to help prevent the spread of COVID-19 once you've been exposed to someone with the infection. CDC advises quarantine for 5 days after exposure, followed by 5 days of wearing a mask around others. But they recognize the hardship for many who are unable to quarantine. CDC advises if you can’t quarantine, you must wear a mask at all times when around others for 10 days after exposure. If you develop symptoms, stay home.

Get tested at least 5 days after being exposed and monitor for symptoms. If your test result is positive, isolate at home for 5 days. If you don't have symptoms or your symptoms are getting better after 5 days, you can leave your house. Continue to wear a mask around others for 5 more days. If you have a fever, continue to stay home until your fever goes away. If your test is negative, you can stop isolation 5 days after exposure, but wear a mask around others for 10 days after exposure.

  • Stay informed of your community's instructions as this advice may change as new variants of the virus appear.

  • Take your temperature every morning and evening This is to check for fever. Keep a record of the readings. If possible, stay away from others, especially those who are at higher risk of getting very sick from COVID-19.

  • Watch for other symptoms of the virus such as coughing and shortness of breath. If you develop any symptoms, isolate yourself right away. Call your provider first before going to any clinic or hospital. See the CDC's coronavirus self-checker.

  • If you've had COVID-19 in the past and have been re-exposed, contact your healthcare provider for advice. You are less likely to develop COVID-19 again, but it's possible. This is because of new variants of the virus and because some people can't mount a strong immune response after the illness. CDC recommends for all those exposed to get tested 5 days after exposure. If you have symptoms, start quarantine right away and continue until a negative test confirms symptoms are not from COVID-19.

How to manage 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 well-fitting 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 your nose, mouth, and chin. Make sure there is no air is flowing from the top, bottom, or sides of your mask.

  • 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 COVID-19

  • COVID-19 is mainly a respiratory illness but more severe cases can involve many parts of the body.

  • It's caused by a new (novel) type of coronavirus called SARS-CoV-2. The virus is mainly 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, or the skin of someone with the infection, and then touch your eyes, nose, or mouth.

  • The best way to protect yourself from COVID-19 is to get vaccinated and to follow safety precautions. Wash your hands often and disinfect high touch surfaces like door knobs. Monitor for symptoms of COVID-19. Follow safety precautions, including social distancing and mask requirements. See CDC's safety precautions.

  • Know your community's COVID-19 Community Level. If you are in an area of high COVID-19 Community Level, the CDC advises that everyone age 2 or older wear a mask indoors in public areas, even if they are fully vaccinated.

  • Several vaccines are available to prevent COVID-19 in people as young as 6 months of age. Pregnant or breastfeeding people are advised to be vaccinated. The vaccines are given as a shot (injection) in the muscle. Doses vary by age and health status.

  • People age 5 or older can get a COVID-19 booster shot. Talk with your healthcare provider about which vaccine is advised based on age and overall health.

  • 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 given to help your body while it fights the virus. This is known as supportive care. In addition, those with more serious cases or those at risk for serious disease will be offered certain medicines and other treatments aimed at the virus and the inflammation it causes.

  • 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: 7/25/2022

Online Medical Reviewer: Barry Zingman MD
Online Medical Reviewer: L Renee Watson MSN RN
Date Last Reviewed: 9/1/2021
© 2000-2022 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.