At-Home COVID-19 Antigen Test
Test Quick Guide
At-home antigen tests are a method of detecting a current infection with SARS-CoV-2, the coronavirus that causes the illness known as COVID-19.
The test uses a swab to take a sample from the nostrils that is then rapidly analyzed by an included device that typically provides results within 30 minutes.
The most common use of at-home antigen tests is for screening, which is trying to detect cases of COVID-19 before symptoms occur so that the virus is not spread to other people.
About the Test
Purpose of the test
Antigen tests are one method for determining if you have an active infection with the SARS-CoV-2 coronavirus and can be used for screening and diagnosis of COVID-19. The principal role for at-home antigen tests is in screening.
Screening is the term for looking for a disease before any symptoms have appeared. Because SARS-CoV-2 can be spread even when you are asymptomatic, detecting cases with screening can help prevent virus transmission. Rapid antigen tests are frequently used for screening because of their low cost and ability to provide a quick result.
Diagnosis, on the other hand, is testing for a disease after symptoms have started. For COVID-19, molecular tests such as a PCR are considered the standard tests for diagnosis; however, an antigen test may be used when those tests are unavailable.
What does the test measure?
Antigens are proteins that are found on the surface of the SARS-CoV-2 coronavirus. The immune system identifies antigens in order to mobilize an immune response. An at-home antigen test looks for antigens that are specific to SARS-CoV-2 in a swab of cells taken from your nose or the area at the back of your nostril. When significant quantities of the virus are present in the body, these antigens can be detected by the test.
When should I get an at-home COVID-19 antigen test?
The main use for at-home antigen tests is for screening to find SARS-CoV-2 infections before symptoms are present. Examples of situations in which screening may be beneficial include:
- When you have been in close contact with a person who has tested positive for COVID-19
- When you have potentially been exposed to SARS-CoV-2 as a result of travel or attending a large gathering
- When you work or live someplace where many people live together such as a nursing home or correctional facility
- When you are required to show proof of a negative test in order to travel, go to work, or take part in other activities
At-home tests may be useful for screening in some cases, but many screening programs, such as for work or travel, may not accept an at-home test result.
Two other factors can influence antigen testing and should be considered when thinking about taking this type of test:
- Timing of the test and virus exposure: Antigens are usually not detectable for a few days after infection, and antigen levels drop as your body mounts an immune defense against the virus. If a test is done too soon or too late after exposure, it may show no antigens even though you actually have COVID-19. This type of result is known as a false negative.
- Probability of SARS-CoV-2 infection: It is possible to have a positive antigen test when you don’t actually have COVID-19, which is known as a false positive. False positives are more likely when you have a low probability of being infected.
At-home antigen tests are rarely used for diagnosis of COVID-19. A PCR test analyzed by a laboratory is the gold standard for diagnosis, and a PCR may be used to confirm the results of an antigen test, including an at-home antigen test.
Your physician is in the best position to address whether an at-home COVID-19 antigen test or any other type of test is appropriate in your situation. If you have symptoms of COVID-19, you should talk to a doctor promptly.
Benefits and Downsides of At-Home COVID-19 Antigen Test
At-home antigen tests for COVID-19 involve taking a sample from your nostril with a cotton swab. The test kit includes a device that can rapidly analyze this test sample.
In addition to at-home tests, rapid antigen tests can be done in a doctor’s office, pharmacy, health clinic, or other medical settings. Antigen tests can also be done by sending a sample to a laboratory for analysis.
It is useful to consider the relative benefits and downsides of antigen testing done at home compared to testing in a medical office or laboratory.
The main potential benefits of at-home COVID-19 antigen testing include:
- Convenience: An at-home test provides you with the flexibility to take the test when your schedule allows and without having to leave the comfort of home.
- Rapid results: Test kits are designed to quickly analyze your sample, offering results within 15-30 minutes. This rapid result is especially important if the test is being taken for screening since it lets you immediately begin isolation if you test positive.
- Prescription and over-the-counter options: There are at-home antigen tests that are only available with a prescription and others that can be purchased over-the-counter.
Possible downsides of at-home antigen testing include:
- Possible sample contamination: Medical offices have established protocols to help properly take a test sample. When you use an at-home test, you have to take your own sample, which requires carefully following the provided instructions to reduce the chances of sample contamination.
- Costs may not be covered by insurance: If you choose to take an over-the-counter antigen test, you will have to pay the full cost yourself. Prescription at-home antigen tests may be covered by insurance, but you should check with your health care plan about any costs that you would be responsible for.
- Need for follow-up tests: The results of antigen tests often need confirmation with a molecular test like a PCR, especially if your test result is positive.
If you are interested in testing for COVID-19, you can talk with your physician about how these benefits and downsides of at-home testing apply in your situation.
The Best At-Home COVID-19 Tests
The following sections discuss the best options for at-home COVID-19 antigen testing:
Abbott BinaxNOW – COVID‐19 Antigen Self Test
Price: $23.99 (includes 2 tests)
Sample: Lower nasal swab
Results timeline: 15 minutes
The BinaxNOW COVID-19 Antigen Self Test is our pick for the best overall at-home antigen test for SARS-CoV-2. The test has been authorized by the Food and Drug Administration for at-home serial screening. It is simple to use and provides rapid results.
Each BinaxNOW package contains detailed instructions and two separate test kits. The product is designed for serial testing, which means that you perform the test twice within three days, with at least 36 hours between the tests.
In each test kit, you will find all the necessary materials, including a test card, a liquid reagent, and a nasal swab. To take the test, squeeze six drops of the reagent into a slot on the test card. Then swab your nose, place the swab into the slot, and close and seal the card.
Once these steps are complete, it takes 15 minutes to get the results, which are color-coded and displayed on the test card. This test does not produce a formal report, so it is meant for home use rather than documenting test results for travel requirements.
The BinaxNOW test uses a lower nasal swab that is minimally invasive and rarely causes discomfort. It is designed for anyone over the age of 2, but people under 15 should have the test administered by an adult.
The BinaxNOW self-test is made by Abbott, a company with an established track record in the development of medical technologies and pharmaceuticals. In addition to the at-home test, Abbott has developed COVID-19 testing for use by health professionals.
Quidel QuickVue – At-Home OTC COVID-19 Test
Price: See best price on Amazon
Sample: Lower nasal swab
Results timeline: 10 minutes
The Quidel QuickVue At-Home OTC COVID-19 Test is an FDA-authorized method for rapidly and conveniently performing antigen testing for SARS-CoV-2. With results that are available in 10 minutes, it is our pick for the fastest at-home COVID-19 antigen test.
The QuickVue test is designed for serial testing, which involves taking more than one test in a short period of time to help ensure accurate results. In this case, you take the QuickVue rapid antigen test twice within three days, with a minimum of 36 hours between tests.
Each pack comes with two at-home test kits and includes full instructions and the materials to perform the antigen analysis. To take the test, insert a nasal swab into the lower part of your nostrils. This type of swab is unlikely to cause discomfort. Once you have obtained the sample, swirl it in a small vial with a chemical reagent. Then briefly dip a special test strip into the vial and remove it.
Results are displayed on the test strip in 10 minutes. The color-coded results are easy to understand, but it is important to know that you will not have any formal test report.
This test can be self-administered by anyone 15 or older. It can also be performed on anyone over the age of 2 with adult assistance.
Quidel has been researching and developing various types of rapid test kits since 1986. In addition to the COVID-19 antigen test, the company offers an at-home test for the influenza A and B viruses.
Interpreting At-Home Test Results
The result of the test is listed as either positive or negative unless the test kit could not properly process the sample, in which case, the result may come back as invalid. A positive result means that antigens to SARS-CoV-2 were found in your sample, and a negative result means they were not.
In most cases, a positive test indicates an active case of COVID-19, but the results of antigen tests need to be interpreted in the context of your perceived likelihood of testing positive. This is known as your pre-test probability of a positive or negative result. Factors that can influence your pre-test probabilities include the extent of community spread of SARS-CoV-2 where you live, your exposure to potentially infected people, and whether you have symptoms of COVID-19.
Considering pre-test probability helps your doctor evaluate whether your test result could be a false positive or a false negative. Based on that evaluation, they may recommend another test like a PCR to confirm the result of the at-home antigen test.
You should follow rigorous protocols for isolation if you test positive on an at-home test even if you think it might be a false positive. Follow these isolation measures until you have had a chance to review your test result with your doctor who can provide more specific guidance about how long you should be isolated.
Are test results accurate?
At-home antigen testing is dependable but not perfect. Factors that can affect accuracy include:
- Improper sample collection: Without an adequate and uncontaminated sample, the test result can be inaccurate or invalid.
- Potential false positives: A positive result can occur when you aren’t actually infected with SARS-CoV-2. The risk of a false positive is highest when you have a low pre-test probability of testing positive.
- Testing too early or late: You can have COVID-19 and test negative if the test is conducted too soon after infection when antigens have not reached detectable levels. A false negative can also occur when testing too late after infection because antigens decrease as the immune system fights the virus.
Your doctor can take these factors into consideration when interpreting your at-home test result. The doctor can also advise you about whether another test, like a PCR, would be beneficial to confirm the findings of your at-home antigen test.
Do I need follow-up tests?
Follow-up testing may be necessary to confirm the findings of an at-home COVID-19 antigen test. Molecular tests like a PCR are regarded as more accurate in identifying an active infection, so a positive at-home test may warrant follow-up testing with a PCR.
Questions for your doctor after at-home testing
Your doctor can help you understand the significance of an at-home antigen test for COVID-19. Some questions that may advance your discussion with your physician include:
- Do I need to follow any particular precautions based on my test result?
- Is there a possibility that my test result is inaccurate?
- Are there any follow-up tests that should be done?
At-home antigen tests are just one kind of test that has been developed since the start of the COVID-19 pandemic. The following sections compare and contrast at-home antigen tests with other types of tests for COVID-19.
COVID-19 antigen testing at home vs. at a doctor’s office
All antigen tests for COVID-19 use a sample that is taken from your nostril. The sample can be taken in a medical office or at home. A doctor, nurse, or technician with experience taking test samples may be able to avoid potential problems of specimen contamination or related errors. However, for many people, going to an office for the test is less convenient than taking the test at home.
Test samples can be analyzed with either a rapid test or in a laboratory. Rapid tests can be done in a medical setting or at-home. Tests that involve analysis by a laboratory are not currently available at home.
Rapid tests provide results in under an hour while laboratory-analyzed tests can take one to three days. Laboratory-based analysis is considered to be slightly more accurate than rapid tests, but both types often require confirmatory testing with a PCR.
At-home COVID-19 antigen tests vs. PCR tests
PCR and antigen tests for COVID-19 are similar in that they look for signs of a SARS-CoV-2 infection in the upper respiratory tract. Instead of antigens, though, PCR tests look for the genetic material of the virus, and this testing method is considered to be more accurate in diagnosing COVID-19.
Antigen tests are only authorized to use a sample from the nose or behind the nose, but a PCR can be conducted on these samples as well as those from the throat or saliva.
Rapid test options are available for both PCR and antigen tests, but PCR is more frequently analyzed by a laboratory while antigen tests are more often done as rapid tests.
All current at-home antigen tests are rapid tests. Some at-home PCR tests are rapid tests while others require sending the sample by mail from your home to a laboratory where it can be analyzed. For both at-home antigen and PCR tests, there are options available by prescription and over-the-counter.
At-home COVID-19 antigen tests vs. antibody tests
The key difference between antigen tests and antibody tests is that antigen tests can identify current infection while antibody tests can identify a past infection.
Antigens are detectable promptly after infection and soon decrease in number. Antibodies are produced a few weeks after infection and can last for many months. As a result, antigen tests, but not antibody tests, can be used for screening and diagnosis of COVID-19.
The test sample is also different for these two tests. An antibody test analyzes the blood while an antigen test is done with a swab from the nose or back of the nose.
At-home test options exist for both antigen and antibody tests, but the only authorized at-home antibody tests require a sample that is collected at home to be sent to a laboratory where it can be processed.
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