Should I Get a COVID-19 Test?
Your COVID-19 Testing Questions Answered
Published September 2021
Jeffrey Kopin, MD, chief medical officer at Northwestern Medicine Lake Forest Hospital, answers common questions about COVID-19 testing. Note that these are general guidelines for COVID-19 testing. Consult your physician before you pursue testing and to learn what to do after you get your results.
Your best defense against COVID-19 is vaccination. COVID-19 vaccines are shown to be safe and effective. To find a vaccination location near you, go to vaccines.gov. Northwestern Medicine currently offers one-dose or two-dose vaccines at select locations. Availability of each vaccine depends on the location.
Who should get tested for COVID-19?
Northwestern Medicine follows the Centers for Disease Control and Prevention (CDC) guidelines for testing. You should consider COVID-19 testing if:
- You have symptoms of COVID-19, regardless of vaccination status or prior infection.
- You have had close contact (within 6 feet for a total of 15 minutes or more over a 24-hour period) with someone with confirmed COVID-19.
- If you have been fully vaccinated, you should be tested three to five days following a known exposure to someone with suspected or confirmed COVID-19, and wear a mask in public indoor settings for 14 days or until they receive a negative test result.
- If you have tested positive for COVID-19 within the past three months and recovered, you do not need to get tested following an exposure as long as you do not develop new symptoms.
- You are unvaccinated and have taken part in activities that do not allow for physical distancing as needed to avoid exposure, such as traveling, attending large gatherings or being in crowded or poorly ventilated indoor settings.
- You have been asked or referred to get tested by your healthcare provider or health department.
If you get tested because you have symptoms or were potentially exposed to the virus, you should stay away from others pending test results and follow the advice of your healthcare provider or a public health professional.
Where can I get tested?
A Northwestern Medicine physician's order is required for a COVID-19 test at Northwestern Medicine. If you do not have an order for testing, contact your Northwestern Medicine physician or schedule a telehealth visit at a Northwestern Medicine Immediate Care Center to determine if you need a COVID-19 test.
What can I expect from a COVID-19 test?
Diagnostic COVID-19 tests show if you have an active COVID-19 infection. They are different from antibody (also known as serology) tests, which may show if you have antibodies from a past COVID-19 infection or vaccination.
There are two main types of diagnostic COVID-19 tests; the difference between is how your sample is tested in a laboratory.
- Molecular tests look for the SARS-CoV-2 virus, which causes COVID-19, by detecting its genetic material.
- Antigen tests do not look for the SARS-CoV-2 virus itself. Instead, they test for certain proteins found in the virus.
COVID-19 testing methods will vary by location. Both antigen and molecular test samples are mainly collected in one of two ways:
- During an anterior nasal swab, your provider will slowly twist a cotton swab along the inside of both of your nostrils for about 15 seconds.
- During a deep nasal swab, your provider will insert a longer swab about 1 inch into both of your upper nasal cavities and twist it for about 15 seconds.
Some molecular tests are being conducted on saliva that is collected in a tube.
How long will it take to get my test results back?
The timing of test results depends on the location and type of test used. Antigen tests are typically faster than molecular tests.
- Antigen test results may be available in as little as 15 minutes.
- Molecular test results can be returned in less than 24 hours but may take up to several days.
Which test is the most accurate?
There is not enough research yet to answer this definitively. However, a negative antigen test result may need to be confirmed with a molecular test, especially if you have COVID-19 symptoms. Molecular tests seldom need to be repeated and appear to be more accurate, as they prove the physical existence of the SARS-CoV-2 virus inside your system.
What should I do while I wait for my results?
If you were tested due to symptoms of infection or possible exposure to COVID-19, you should self-isolate while you wait for results to avoid the possible spread of COVID-19.
What happens if I test positive?
If you test positive for COVID-19:
- Call your physician.
- Take steps to avoid infecting others.
- Stay home and away from other people or pets in your home until your symptoms stop.
- Rest and hydrate.
- Continue to monitor your symptoms and consult your physician, especially if symptoms worsen.
- Self-isolate for 10 days, even if you have no COVID-19 symptoms.
If your symptoms become severe, go to the nearest emergency department.
If I test positive, when can I stop self-isolation?
You can stop self-isolating 10 days after your symptoms first appeared as long as your symptoms have improved and you have not had a fever for 24 hours (without the aid of fever-reducing medication like acetaminophen). Please note that loss of taste and smell may continue for weeks or months after your other symptoms improve; this is not a reason to continue self-isolating.
If your symptoms have improved and your fever is gone, talk to your physician about resuming contact with others. Regardless of symptoms, your physician may recommend getting retested to ensure that the infection has cleared before breaking your self-isolation.
What happens if I test negative?
If you test negative, it means that you were not infected with SARS-CoV-2 at the time of the test. But, this does not mean that you are not at risk of getting COVID-19. To avoid future infection and slow the spread of the virus: