How Reliable Are At-Home COVID Tests?
Rapid at home COVID-19 tests are used to determine if you have the virus that causes COVID-19. The U.S. Food and Drug Administration has sanctioned a number of at-home COVID-19 tests. Several manufacturers make these tests. The majority of at-home COVID-19 tests are antigen tests. These tests yield results within about 15 minutes.
Polymerase chain reaction (PCR) tests are more accurate, but it takes a few days for the results to come back from the lab, leaving a potentially infected person unaware that they are transmitting COVID-19 to others.1 For this reason, many people opt for at-home COVID tests.
Table of Contents
Types of At-Home COVID Tests and Their Accuracy
Two types of COVID-19 tests are available: antigen and polymerase chain reaction (PCR).
Antigen tests
Antigens are substances such as proteins that can stimulate an immune response. These short sequences of amino acids identify a protein as belonging to a certain cell type or organism; in the same way as your address and zip code, identify your home. The COVID-19 tests bind to these antigens and display a chemical indicator if they are present. If the SARS-CoV-2 virus is present, the test will detect its specific antigen and display a positive result.
Antigen tests rely on the presence of the antigen to accurately detect the virus that causes COVID-19. If you are too early in your illness or you do not have symptoms, your test may come back negative. This is why the FDA recommends serial retesting. Antigen tests are accurate about 80% of the time.
PCR tests
PCR tests amplify short protein sequences before testing by making hundreds of copies of the sequence. These tests are more accurate than antigen tests, especially early in the course of illness and in people who do not have symptoms. PCR tests are accurate about 95% of the time.
PCR tests can have a higher false positive rate. Because a small amount of antigen is amplified and then analyzed, a small amount of virus can be identified. This is important as the COVID-19 virus can be shed for longer (about 17 days) than the infectious period (about nine days).2
Both antigen and PCR tests require swabbing of the nose or throat and performing the COVID-19 test according to the instructions. User error can also impact COVID-19 test accuracy.
Options for At-Home COVID Test Kits
Examples of antigen tests include:
- BinaxNOW COVID-19 test
- CareStart COVID-19 test
- Flowflex COVID-19 test
- Advin COVID-19 test
- NIDS COVID-19 test
- Fastep COVID-19 test
- Azure FaSTEP COVID-19 test
- BD Veritor At-Home COVID-19 test
- Hotgen COVID-19 test
- Bio-Self COVID-19 test
- QuickVue COVID-19 test
- And many others
Examples of molecular at-home tests:
- Metrix COVID-19 test
- Cue COVID-19 test
- Lucira CHECK-IT COVID-19 test
Other Types of COVID Tests
Samples for PCR tests are collected at home and then sent to a lab for amplification and analysis. For this reason, PCR tests are more accurate but take longer to get the results.
When Should You Take a COVID Test?
Consider taking an at-home COVID-19 test if you have symptoms of COVID-19. There are several COVID-19 screening questions you can ask yourself to determine whether you are likely to have COVID-19 or not.
COVID-19 symptoms usually appear two to 14 days into infection. Symptoms associated with COVID-19 include the following:
- Temperature over 100.4º F without taking any fever-reducing medications
- Cough
- Loss of taste or smell
- Shortness of breath
- Sore throat
- Muscle aches
- Chills
- New or unusual headache
- Nausea
- Vomiting
- Diarrhea
- Loss of appetite
Once you have symptoms, the viral load is high, and the test should pick up SARS-CoV-2 antigens.
How To Interpret At-Home COVID Test Results
Each test has a slightly different way of expressing a positive or negative result. All have instructions for doing the test and reading the results. Some test kits also have links to videos that explain the process.
Typically, the steps to taking a COVID-19 rapid antigen at-home test include the following:
- Wash your hands with soap and water.
- Open the test kit. You should see a collection swab, a test strip, and a small vial of liquid.
- Swab the internal surface of both nostrils. Rotate the swab inside your nostril at least five times.
- Insert your swab (where you collected the specimen) into the liquid in the vial.
- Stir the swab at least 15 times in the liquid.
- Squeeze the sides of the vial together and slowly pull the swab out, squeezing the liquid from the swab.
- Open the test strip. Squeeze three drops of the solution onto the test strip.
- Set a timer for 15 minutes.
- Read your test results.
There are two potential lines on your COVID-19 test strip at the end of the test.
- C line: this is the “control” line. If this line is not visible, then the test is not accurate. You will need to retest.
- T line: This line indicates whether your test is positive or negative. The test is positive if the “T line” is present, no matter how faint. If no line is visible at the “T, ” the test is negative.
What To Do If You Get a Positive Test
If you get a positive test result, it is important to isolate yourself so that you do not transmit COVID-19 to others. You may also want to notify people you have recently been in contact with to advise them of your positive test results.
To learn how to manage your current symptoms and learn about warning symptoms that may indicate more serious disease, contact an online doctor at TelegraMD. Online doctors can evaluate your symptoms, look at your COVID-19 test results, provide online diagnoses, and discuss treatment options. If warranted, your doctor can prescribe online and send your online prescription to a pharmacy. Whether or not you have insurance, you are likely to find that seeing an online doctor is an easy and cost-effective way to have a doctor’s visit for many conditions.
What To Do If You Get a Negative Test
As of November 17, 2022 (accessed 5/27/23), the U.S. Food and Drug Administration advises people to do serial COVID-19 testing if they have symptoms consistent with COVID-19 and receive negative test results. Doing tests every few days could help prevent the spread of infection if the COVID-19 test results are a false negative.
If you have had COVID-19 symptoms for a few days and your test is negative, you likely do not have a COVID-19 infection. Another virus or other pathogen may be causing your symptoms. If you do not have any symptoms of illness and your test results are negative, you probably do not have COVID-19.
If you have very recent symptoms of COVID-19 and a false test result, you may still have COVID-19. Wear a mask around people and isolate, if possible, until your symptoms resolve, or you receive another diagnosis and are no longer contagious.
The Affordability of At-Home COVID Tests
COVID-19 at-home tests cost about $10.00 for each test. Free COVID-19 tests are sometimes available at health departments and distributed through your local libraries.
Disclaimer
While we strive to always provide accurate, current, and safe advice in all of our articles and guides, it’s important to stress that they are no substitute for medical advice from a doctor or healthcare provider. You should always consult a practicing professional who can diagnose your specific case. The content we’ve included in this guide is merely meant to be informational and does not constitute medical advice.
References:
- Crozier A, Rajan S, Buchan I, McKee M. Put to the test: use of rapid testing technologies for COVID-19. BMJ. 2021;372:n208 doi:10.1136/bmj.n208
- Cevik M, Tate M, Lloyd O, Maraolo AE, Schafers J, Ho A. SARS-CoV-2, SARS-CoV-1 and MERS-CoV viral load dynamics, duration of viral shedding and infectiousness: a living systematic review and meta-analysis.SSRN2020. [Preprint.] doi:10.2139/ssrn.3677918
