Rapid Tests

Rapid Tests
A small group of diverse nursing students sit around a boardroom table as they listen attentively to their teacher and lead doctor. They are each dressed in medical scrubs and sitting with papers out in front of them. The doctor is holding out a clipboard with a document on it as she reviews it with the group.

Rapid tests, also known as rapid diagnostic tests or RDTs, are easy-to-use tests that provide quick results, usually in 20 minutes or less. Unlike most standard tests, which have to be sent to a lab, rapid tests are done and provide results at the point of care. The point of care is the place where you are getting care. It can include your provider’s office, a clinic, or even your own home.

Rapids tests usually include the following steps:

  • You will provide a sample of your body fluid, such as blood, urine, saliva, or nasal secretions.
  • The sample is mixed with a special substance that will cause a chemical reaction if a disease or other condition is present.
  • Results will show on a dipstick or rapid test cassette.
    • A dipstick is a thin, plastic strip that’s coated with chemicals. If the test is positive, the dipstick will change colors when placed in the sample.
    • A rapid test cassette is a small, plastic case that has a well that holds the sample. The well will show a letter or a symbol to indicate the result.

    Most rapid tests are highly accurate, but the results are not always as accurate as standard lab tests.

    Other names: rapid diagnostic tests, RDT’s point-of-care tests

    How are they used?

    Rapid tests are most often used to diagnose infectious diseases, including:

    • Flu
    • Strep throat
    • Malaria
    • HIV
    • COVID 19. Rapid tests for COVID-19 usually provide results in about 30 minutes.

    Rapid tests are also used in certain home-based tests, such as pregnancy tests.

    What are the advantages and disadvantages of rapid tests?

    The advantages of rapid tests include:

    • Fast results. This may allow you to get treatment faster. Faster treatment can reduce the severity of your symptoms, and may help prevent the spread of disease
    • Easy to use. They can be done by non-medical workers and volunteers who have been trained to do the test. You may even be able to perform a rapid test on yourself.
    • Little or no special equipment required. This is especially useful in areas with limited resources or access to specialized labs.

    Disadvantages of rapid tests:

    • Lower sensitivity than lab tests. Sensitivity means how well a test can identify a disease or condition. Rapid tests are not as good as lab tests at finding diseases in the earliest stages of infection.
    • False negatives are more common. A false negative result means your test shows you don’t have a disease or condition, but you actually do have it.

    Providers will often take a second sample and send it to a lab for testing to confirm or rule out the results of a rapid test. But you may be able to get treatment and help prevent the spread of disease while you wait for lab results.

    Is there anything else I need to know about rapid tests?

    Home based rapid tests are available for COVID-19. Like other rapid tests, the rapid COVID-19 tests have lower sensitivity than standard lab tests. But getting fast, home-based results may help prevent the spread of disease. Talk to your health care provider to learn more about these home-based tests.

    Courtesy of MedlinePlus from the National Library of Medicine.