Types of COVID-19 Tests

Updated June 28, 2022

Report positive test results to the UW COVID-19 Response and Prevention Team.

Follow the COVID-19 Public Health Guidance and Requirements Flowchart if you test positive, have COVID-19 symptoms, or have a close contact exposure. 

COVID-19 viral tests are diagnostic tests that can tell you whether you are currently infected with the virus that causes COVID-19 at the time of the test. COVID-19 viral diagnostic tests can be either antigen tests (e.g., rapid self-test) or molecular tests (e.g., PCR).

When to test

  • If you have COVID-19 symptoms such as a sore throat, cough, fever, congestion
  • If you were exposed to someone who has COVID -19
  • Returning to the University after academic breaks
  • Before and after a large social event or gathering
  • When you are asked to get tested by the University, the local health department, or your healthcare provider
  • Before and after travel per CDC travel guidelines
  • Optional: At the end of your 5-day isolation period, after you are fever free and symptoms have improved, to help evaluate if you may still be infectious to others

Which test to use

Consider these factors when choosing between a molecular PCR test and an antigen test.

PCR test  Antigen test
  1. Best for early diagnosis of an infection, even in people who do not have symptoms
  2. When you start developing COVID-19 symptoms
  3. After close contact exposure to someone with COVID-19: Test at least 5 days after exposure. If you test negative, consider testing again 1-2 days later.
  4. Screening prior to a social gathering, activity, venue entrance or event, or before and after travel when you are symptom-free
  5. If you need to confirm the results of an antigen test
  6. For travel or venues/events requiring a negative test result from an antigen or PCR test from a point-of-care or testing provider

Do not get a PCR test if you had COVID-19 within the past 90 days (the test may be intermittently positive even after you are no longer infectious).

  1. Best for screening and rapidly identifying infectious individuals with symptoms and in high transmission settings
  2. Upon return to campus after academic breaks
  3. If you have COVID-19 and have isolated for at least 5 full days and your symptoms are improved (or you have no symptoms), and you want to check if you are still infectious before returning to regular activities 
  4. If you have symptoms and cannot get access to timely PCR testing: Test the day after symptoms develop, or do 2 tests at least 24 hours and no more than 48 hours apart (if the first one is negative).
  5. If you have recovered from COVID-19 within the last 90 days and you have a new COVID-19 exposure and develop new COVID-19 symptoms
  6. Rapid screening prior to a social gathering or activity when you are symptom-free (higher risk of false negative so continue to take additional precautions)
  7. At least 5 days after close contact exposure (If you test negative for COVID-19, consider testing again 1 to 2 days after your first test.); multiple negative tests increase the confidence that you are not infected with the SARS-CoV-2 virus.

Antigen self-tests (home tests) are not accepted:

  • To meet travel testing requirements
  • For entry to some establishments or events requiring proof of a negative test

For healthcare facility workers (and trainees) in certain situations; check with your hospital or clinic’s employee health center.

Accuracy of the results

PCR test  Antigen test
  • Highly sensitive, highly specific test
  • Positive and negative results are highly reliable when used appropriately
  • Less sensitive test, but very accurate when a person has high viral levels (when they are experiencing symptoms) and therefore likely to be most contagious 
  • May miss low levels of virus in a person, may show false negatives in asymptomatic people or in people in the first few days of their infection 
  • If your result is negative and your symptoms worsen (or you are concerned about a false negative result after a close contact or suspected exposure): Take another antigen test within 24 to 48 hours or take a PCR test and isolate while you await results. 
  • Positive results are especially reliable if you have symptoms and it is a period of transmission rates in the community are high.  
  • False positives can occasionally occur when transmission rates in the community are low. 

Molecular (e.g., PCR) tests

  • Molecular tests look for the presence of SARS-CoV-2 virus genetic material (nucleic acid or RNA fragments) in a sample. Molecular tests include PCR tests, which are reliably accurate.
  • Molecular tests are more sensitive than an antigen tests; they can detect much smaller amounts of virus in the body, and therefore detect an infection earlier and can continue to detect remnants of the viral RNA in the body well after the infection has resolved.
  • Most molecular tests are administered at a point-of-care site (e.g., health care provider, pharmacy, public health testing site, private lab). Most molecular tests must be processed in a laboratory so it may take hours to days to get your results.
  • Husky Coronavirus Testing, a UW voluntary research study, provides lab-processed PCR tests.
  • Antibody or serology tests are not viral tests and should not be used to diagnose a current infection.

Antigen tests

  • COVID-19 antigen tests look for the presence of specific SARS-CoV-2 virus protein structures (antigens) in a sample. Antigen tests can give you rapid results- typically in less than 30 minutes.
  • Antigen tests are helpful in providing fast, generally reliable results when you have COVID-19 symptoms.  However, antigen tests are less sensitive than molecular tests; they may miss an early infection when there are low levels of virus in the body, also known as a false negative test result. 
  • Antigen tests can be administered in point-of-care settings (provided and interpreted by health care providers, testing facilities, pharmacies etc.), or sold online and at retail locations and administered at home (in self-test form).

Refer to the Public Health – Seattle & King County blog that further explains differences between rapid antigen tests and molecular PCR tests.

How to get a COVID-19 test

Locations that offer PCR and antigen tests for personal use are listed on the University's COVID-19 testing webpage.

University units that utilize rapid antigen tests to support their operations can order them with a budget number from the UW Clean and Safe Storefront.

How to use a rapid antigen self-test

Watch the CDC video How to use a self-test and follow the instructions provided in the video.

Specific instructions are also provided by the manufacturer in the self-test packaging, follow these specific instructions closely to best ensure an accurate result. 

Watch the CDC video How to interpret self-test results.

If you get a positive test result:

More information