6/25/20 | What to Know about Testing for COVID-19

COVID-19 tests are important tools for diagnosing COVID-19 infection. There are limitations to any test and these tests work best in diagnosing people who have symptoms of COVID-19 infection.

Who should get tested?

Anyone who develops new symptoms after an exposure to someone with COVID-19 should get tested.  People who have been exposed to someone with COVID-19 but don’t have symptoms can consider testing but should wait until the right time to prevent inaccurate results.

When should I get tested?

If you have symptoms concerning for COVID-19, you should get tested.  After exposure to someone with COVID-19, you are at potential risk for developing infection for 14 days after the exposure.  If you have been exposed to someone with COVID-19 but don’t have new symptoms, it is important to wait for 8 days after the exposure to reduce the chances of an inaccurate test.

Why should I wait to get tested?

It takes time for the SARS CoV-2 virus that causes COVID-19 to become detectable, even with the sensitive tests being used.  For example, getting a test the day after an exposure gives you a 100% chance of a negative test even if you later develop infection.

Where should I get tested?

Several testing sites are available throughout the San Antonio area and are listed on the San Antonio Metro Health web site.


It is not advised to go to the Emergency Center at a hospital just for testing.  Emergency Centers at hospitals throughout the city are very busy taking care of symptomatic patients with COVID-19.  If you go to one of these centers for testing, you might potentially become exposed to someone with symptomatic COVID-19 disease waiting to receive medical care.

What does a negative test result mean?

If you are asymptomatic but have been exposed to someone with COVID-19, it means that you don’t have detectable COVID-19 at the time of the test but it doesn’t change the 14-day window of infection risk you have from exposure.  You should continue to monitor twice daily for fever and symptoms for the full 14 days.

What does a positive test result mean?

You have detectable COVID-19 and can potentially transmit infection to others.  You should self-isolate and follow the instructions provided by the testing site that has provided your results.  Additional information on what to do can be found on the CDC web site.


What kinds of tests are available for COVID-19?

There are two main kinds of tests for COVID-19: direct viral tests (such as PCR and antigen tests) and antibody tests.

  • Direct viral tests directly detect parts of the SARS-CoV2 virus that causes COVID-19.  They are the recommended tests for diagnosing acute infection. While COVID-19 direct viral tests are generally accurate, they only provide results for the moment in time that the test is collected – kind of like taking a picture with a camera.
  • Antibody tests do not detect the SARS-CoV2 virus that causes COVID-19 directly but instead detect antibodies to the virus, part of the human body’s response to an infection.  Antibody tests are not recommended for diagnosing acute infection.  Some of the available antibody tests are less specific and will detect antibodies to other types of coronaviruses that cause the common cold and not COVID-19.  It is unknown at this time if having antibodies for COVID-19 actually provides protection from re-infection
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