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COVID-19 Testing
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Diagnostic Tests

COVID-19 Testing

COVID-19 is a disease caused by the SARS-CoV-2 virus, and testing is used to identify current or past infections.

Overview

COVID-19 (coronavirus disease 2019) is a disease caused by a virus called SARS-CoV-2. There are two types of tests for this virus:

  • A viral test tells you if you have a current infection. Viral tests can either be rapid tests or laboratory tests:
    • Rapid tests can be done in minutes. They are often antigen tests, which look for specific proteins from the virus. Some rapid tests are self-tests which you can do at home.
    • Laboratory tests can take days to complete and include PCR tests.
  • An antibody (serology) test might tell you if you had a past infection.

How to Get Tested

If you need a COVID-19 test, you can:

  • Buy a self-test online or at a store. Make sure that the test you buy has been authorized by the U.S. Food and Drug Administration (FDA).
  • Check your state or local health department's website for information on testing in your area.
  • Contact your health care provider.

Important Considerations

Even if your COVID-19 viral test is negative (the test did not detect the virus), you should still take steps to protect yourself and others.

Centers for Disease Control and Prevention

Frequently Asked Questions

If you develop symptoms, test immediately. If you were exposed but have no symptoms, wait at least 5 full days after the exposure before taking a test. Testing too early can lead to a false-negative result because viral levels in your nasal passages may not yet be high enough to detect.
PCR tests detect tiny fragments of viral genetic material and can remain positive for weeks or even up to 90 days after your initial infection, long after you are no longer contagious. Because non-infectious viral debris lingers, PCR tests are not recommended to determine when it is safe to end isolation.
single negative rapid antigen test does not rule out infection. The FDA recommends repeating the test 48 hours later. If you remain symptomatic and test negative on the second test, take a third rapid test after another 48 hours or get a laboratory-based PCR test, which is significantly more sensitive.
No. While a positive antibody (serology) test indicates that your immune system responded to a prior infection or vaccination, it does not measure your current level of protection or guarantee immunity against reinfection, particularly from new variants. Antibody tests should never be used to diagnose an active infection.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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