Public Health

How Long After Exposure Should You Get A COVID-19 Test?

Khang T. Vuong, MHA
Khang T. Vuong, MHA15 Sep 2021

With the increasing prevalence of the Delta variant, vaccinated persons also need to be aware of what precautions to take after being exposed to COVID-19. Official CDC guidance does not require fully vaccinated persons to quarantine after exposure but recommends getting a COVID-19 test 3-5 days after exposure. Even if you are not experiencing symptoms, you should wear a mask indoors for 14 days after exposure to prevent spreading the virus.

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When to Get Tested for COVID-19 After Exposure

If you were recently exposed to COVID-19, it is likely you were exposed to the Delta variant. You will most likely test positive within 4 days after being exposed to the Delta variant, but a negative test does not necessarily mean you are not infected. If you are exposed and test negative, you should obtain a second test in the next few days.

Prevalence of the Delta Variant

The Delta variant is the dominant strain in the country and is the most contagious to date. Below is a graphic depicting the proportion of each strain by region, with the Delta variant in orange.

Proportion of Strain of COVID-19 by Region

What to Do if You Were Exposed

According to current CDC guidelines, anyone who has been in close contact with someone with COVID-19 should stay home for 10 days (quarantine) unless:

  • You are fully vaccinated and show no symptoms of COVID-19. Although, you should still get tested 3-5 days after exposure and wear a mask indoors for 14 days or until a negative test.


  • You had COVID-19 within the previous 3 months and have recovered and do not have COVID-19 symptoms (for example, cough, shortness of breath)

Close contact refers to being within 6 feet of an infected person for a total of 15 minutes or more over a 24-hour period. Close contact includes caring for someone infected with COVID-19, living with someone infected with COVID-19, or being exposed to respiratory droplets from someone infected (like being coughed or sneezed on).

The next step is to notify anyone you have come in contact with since being exposed. You can spread the virus for two days before you test positive, even if you are not experiencing symptoms. Make sure you monitor your symptoms regularly and quarantine when necessary.

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Types of COVID-19 tests

There are currently two main types of tests for COVID-19: diagnostic tests and antibody tests. Diagnostic tests can tell you if you are currently infected with COVID-19, while antibody tests detect if you have immune cells in your blood produced by the SARS-CoV-2 virus.

Differences Between Diagnostic Tests and Antibody Tests

Diagnostic TestsAntibody Test
Can tell if you have an active infectionCan tell if you were previously infected or have immunity from vaccination
Collected with a nasal swab, throat swab, or salivaCollected from blood from a finger prick or blood drawn by a medical professional
Can be reported in as little as 15 minutes for a rapid test, or 24 hours for a PCR testResults are usually available in 48 hours

Antigen Test: This test, also referred to as a rapid test, is also used to detect an active infection of COVID-19. The sample for this test is taken through a nasal swab, and test results are typically available in less than one hour.

However, these tests are more prone to a false negative result than the PCR tests. Your provider may want to confirm a negative antigen test by doing a PCR test as well. 

PCR Test: This test detects an active infection of COVID-19. The sample for this test can either be taken through a nasal swab or a saliva sample. The time it takes for results for PCR tests depends on the volume of tests at that location.

Antibody Test: This test detects a past infection of COVID-19. The sample for an antibody test is done by drawing blood from the arm. This test is not used to diagnose a current infection with COVID-19. 

Reliability of COVID-19 Tests

Getting a negative COVID-19  test result cannot certainly rule out the chance of having coronavirus. If you were in close contact with someone who has COVID-19 and is not vaccinated, you should self-quarantine for 7 additional days after a negative test to avoid spreading the virus to others. 

COVID-19 Testing After Exposure Frequently Asked Questions (FAQs)

After being exposed to COVID-19, the best way to protect others is to quarantine yourself for 10 days. Some local health departments have shorter quarantine requirements. If you were exposed, it is recommended to get tested within 3-5 days to know if you are infected or not. Below we answer some additional questions.

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Should I get a rapid or PCR test for COVID-19?

In general, the standard PCR tests are more accurate than the rapid antigen tests, meaning that you are more likely to get a false negative result from a rapid test. Therefore, to have the most accurate results, you should get a standard PCR test. 

However, if you need to get test results immediately to return to work, the rapid test may be the best option for you.

What should I do if I was exposed to someone with COVID-19? 

As a general rule, the centers for disease control (CDC) constitute an exposure as being within 6 feet of someone who has COVID-19 for at least 15 minutes within a 24 hour period. However, these guidelines are not exhaustive - you can still get COVID-19 from being in contact with someone for fewer than 15 minutes, even if you are more than 6 feet apart.

If you believe you were exposed to someone with COVID-19, you should immediately isolate yourself for 10 days, even if you do not have symptoms. Since cases are currently rising in the United States, we all must play our part to avoid spreading coronavirus. In addition, you should notify all coworkers, friends, or family members that you have been in contact with. You should contact your doctor about getting a test and monitor your symptoms.

If you get a positive result, the CDC is recommending that you quarantine for 10 additional days. If you are feeling sick during this time, reach out to a health care provider to monitor your symptoms. These quarantine guidelines do not apply to those with severe illness or those who are immunocompromised.

How do I know if I have COVID-19, the flu, or the common cold?

COVID-19, the flu, and the common cold may display different symptoms, allowing you to tell the difference. In general, the best way to know what sickness you have is to get a test for the flu and COVID-19. 

Bottom Line

The guidelines regarding what to do after exposure to COVID-19 is evolving as scientists learn more about the virus. At this time, the most important steps to take are to get vaccinated to protect yourself and get tested after exposure to protect those around you.

Khang T. Vuong, MHA

Khang T. Vuong received his Master of Healthcare Administration from the Milken Institute School of Public Health at the George Washington University. He was named Forbes Healthcare 2021 30 under 30. Vuong spoke at Stanford Medicine X, HIMSS conference, and served as a Fellow at the Bon Secours Health System.