What's the difference between COVID-19 PCR tests, rapid tests, and antibody tests?
COVID-19 PCR tests, rapid antigen tests, and antibody tests all seek to help curb the spread of the COVID-19 virus. What exactly are the differences between the tests, and how do you decide which one to get? Chances are, if you experienced a fever, dry cough, difficulty breathing, or a loss of smell or taste in the past two years, you have first-hand experience with a PCR or rapid antigen test. Below, we discuss key differences between these tests and the antibody test to help you make an informed decision when deciding which COVID-19 test to take.
Types of COVID-19 tests
The first step when you're looking for COVID-19 testing near you is to ask yourself why you are getting tested. COVID-19 testing can be done for a variety of reasons, depending on your motivation. Are you looking for a PCR test near you because you suspect you might have an active infection? Or do you want to take an antibody test to determine if you've been previously infected?
The rapid PCR test
The rapid PCR test is used to determine infection. The test can be processed on-site at most healthcare facilities, and results are available within hours. This test is commonly used when people need to present proof of a negative test in order to travel or return to school or work.
The RT-PCR test
The RT-PCR test takes a few days to process, but results are 98% accurate, which is a few percentage points above the quicker tests.
Antigen tests are generally cheap, easy to find, and can even be administered at home. They are less accurate than PCR tests, but they produce results within 15 minutes.
Antibody tests can detect prior infection to COVID-19. They are not intended to diagnose current infection, but they can help shed light on whether or not you’ve had it in the past. Antibody testing data helps researchers learn more about population-level immunity, and other trends within the virus’ spread. Antibody tests should be taken 3-4 weeks post infection or exposure, or they can lead to a false-negative result, as your body may not have produced enough antibodies yet to be detected. It is also possible to receive a false-positive result if the test detects antibodies from a related coronavirus, such as the common cold.
How are the different tests administered?
The rapid PCR test, RT-PCR test, and Antigen test all three begin with a nasal swab. Occasionally, a throat swab is used for the RT-PCR test, but usually a health professional swabs the inside of your nasal cavity with a very long utensil. This causes discomfort for most people, and individuals with highly sensitive sinus areas may even feel a minimal amount of pain.
Instead of looking for the virus itself, the antibody test screens for the antibodies produced by your body in response to the virus. This requires a blood sample, which is taken either through a finger stick or an intravenous blood draw.
Do they all test for the same thing?
PCR tests use a polymerase chain reaction (PCR) to find genetic material from the COVID-19 virus. This genetic material is present during an active infection, as well as for some time after. An antigen test screens for proteins that are specific to the COVID-19 virus. Like the genetic material in a PCR test, these proteins are found in fluids extracted from the body via nasal or throat swab.
Antibody tests look for specific antibodies to the COVID-19 virus that are produced after an acute infection. Antibodies generally show up 3-4 weeks after infection. These antibodies can also be detected in the bloodstream after being vaccinated against the virus.
Which is the most accurate?
The RT-PCR test is considered the most accurate of the four tests. It is up to 99% accurate, and has a much lower chance of resulting in a false-positive or false-negative. Rapid PCR tests are still 95% accurate, which can be very helpful when making decisions between traveling or isolating. Antibody tests are also considered to be 95% accurate, although they screen only for antibodies and cannot be used to diagnose an active infection.
The CDC describes the accuracy of antigen tests as “moderate to high,” and variable depending on when it’s taken during the course of the virus. Antigen tests also can produce more false-positive or false-negative results than other forms of testing.
Antibody testing is used as a general marker for protection against future COVID-19 infections. By showing whether or not you have been previously infected, it can give you a general idea about whether you are protected against severe infection in the future. However, antibody tests can not provide a definitive measurement of your immunity. You should continue to follow CDC guidelines regarding protecting yourself and others against future infection.
Where can I get tested?
Most hospitals, urgent care facilities, primary care offices, and pharmacies are well-stocked with all four types of tests. There are thousands of mobile testing sites throughout the U.S., and rapid antigen tests are available for purchase at most pharmacies. You can even order free at-home COVID-19 tests through the Department of Health and Human Services.
COVID-19 antibody tests can be purchased through Tripment Health and taken at a lab testing facility near you.
How long before I get my results?
Antigen tests only take 15 minutes and can be done from the comfort of your own home, but they are not the most accurate test. Rapid PCR tests only take a few hours to process, and results are usually given back to the patient within 24 hours. RT-PCR tests must be sent off to a lab to process, and typically take 3-7 days. The wait time for these tests is by far the longest, but they are the only test that delivers 99% accuracy. It's possible to receive results from an antibody test on the same day the sample was collected, but if you went to a facility that processes the sample off-site, you will need to wait a few days.
The time it takes to get your results is also highly dependent on current COVID-19 trends, such as whether or not your geographical zone is currently experiencing a new variant or a general uptick in cases.
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