Rapid antigen tests are most effective when there are high levels of the virus present, such as when you are symptomatic. For this reason, they are less able to detect COVID-19 during the earliest phase of the illness, when low levels of the virus are present. This is why rapid antigen testing may require repeat or serial testing (e.g., re-testing in 24-48-hour intervals). Repeat testing reduces the chances of getting a false negative result. If you are infected with COVID-19 but tested negative early in the course of your illness, you may test positive days later when your virus levels increase. Multiple negative rapid antigen tests increase the confidence that you are not currently infected.
The specific number of times you should take a rapid antigen test depends on your result(s). Positive results from a rapid antigen test are considered highly reliable because these tests are very effective at detecting high amounts of the virus. If you receive a negative test result, the CDC recommends that you test again 48 hours after your initial test, especially if you continue to experience symptoms or have been exposed to COVID-19.
What to do if you have a positive result on a rapid antigen test:
If your rapid antigen test result is positive, this means the virus was detected, and you have an infection. Follow the latest CDC guidance on isolation. If you are at an increased risk for severe illness or have worsening symptoms over time, you should consult a healthcare provider.
What to do if you have a negative result on a rapid antigen test:
If your rapid antigen test result is negative, this means that the virus was not detected, but this doesn’t rule out an infection. You should test again 24-48 hours after your first test, especially if you are experiencing symptoms or have recently been exposed to the virus.
If you continue to receive negative rapid antigen test results, but have symptoms or are otherwise concerned that you could have COVID-19, consider visiting your healthcare provider and getting a PCR test. PCR testing is the most accurate COVID-19 test available, and your healthcare provider can test for other potential viral infections.
Pharmacies, health centers, diagnostic labs, and health departments offer COVID-19 PCR testing and other viral tests. Check where such testing is available in your community using the U.S. Health and Human Services “Test to Treat” testing web page.
Updated November 9, 2023