March 7, 2022
By Dr. Jillian Harrington, PHD, HCLD on July 15, 2022
By now most of us have encountered the need for at least one COVID-19 test whether due to possible exposure, the onset of suspicious symptoms or just a third-party requirement for travel and entry. Today, access to fast, accurate COVID-19 testing is a necessity for those of us who work, travel and live in areas with negative testing requirements.
Fortunately for everyone, COVID-19 testing evolved quickly and most of us have multiple options for testing on demand. Nothing says on demand quite like having a few spare COVID 19 tests you can take right from home. Today, dozens of test kits are available over the counter that are fast, inexpensive, and quite reliable for a first pass test. While you can’t beat convenience, it’s important to know when they are an appropriate option and when they are not. Below we answer a few commonly asked questions about at-home COVID 19 tests.
Right now, all at-home COVID-19 tests are antigen type tests, also called “rapid tests”. They work like other at-home testing kits such as pregnancy, UTI, drug testing and HIV in that they use specific chemicals that react to certain components in the testing sample. At-home COVID-19 test kits are using COVID antibodies to detect COVID antigens.
The main differences between at-home tests will be the sample type (oral saliva or nasal swab) and the result speed - usually between 15-30 minutes. Some tests will work better earlier in the disease timeline as well, so that is another factor to pay attention to.
While at-home testing is very reliable, it is often not quite as sensitive as the testing that can be performed at a clinic. At-home tests are looking for secondary components to what the test is detecting (in this case antigens.) Tests performed in a clinic can detect the component itself (I.e. the actual viral RNA from COVID can be isolated and tested).
At-home tests are appropriate for a quick confirmation of symptoms or exposure to COVID-19. They are most accurate when the viral load is high (and you’re likely already experiencing symptoms). Unfortunately, false negatives can happen if the test is taken too early in the disease cycle before symptoms start. That’s why it’s a good idea to retest 36 hours after a negative test.
At-home tests are also appropriate when you need proof of a negative test for travel and event requirements such as international flights, cruises and concerts. That said, if you’re feeling symptoms know that at-home tests have limits to what they can detect and the method of detection. They are not meant to be confirmatory tests and should be followed up upon by additional testing from your physician’s office.