An infectious-disease doctor answers your questions about how to test yourself for COVID-19.
What You Need to Know About COVID-19 At-Home Testing
Home tests for COVID-19 allow you to test yourself outside of the usual health care setting. In the last several weeks, the FDA has approved multiple new COVID-19 home tests, with likely more coming. Previously, home kits required that you mail your sample to a lab, with results in one to two days. These new tests will be administered, processed, and resulted entirely at home, usually within 15 to 30 minutes. Two of these tests (Lucira and Abbot BinaxNOW) require a prescription, while one (Ellume) can be purchased over the counter. Here, what you need to know about the process.
How do home tests work?
These tests are not as accurate as the gold standard of PCR but come relatively close. This test looks for viral genetic material. PCR testing is slower (24 hours at a minimum), more expensive, and very accurate (if it is a good sample). The Lucira kit also detects genetic material, but instead of PCR, it uses a different amplification process called LAMP. LAMP is faster but slightly less accurate. Both Ellume and BinaxNOW are antigen or rapid tests, detecting a protein piece of the virus. Antigen tests are also faster but less accurate than PCR tests.
Collection of samples differ among the tests: Lucira requires a deep nasal sample like the PCR tests; Ellume requires shallower (mid-turbinate) nasal samples; and BinaxNOW is a more superficial swab of the nostrils. Both Ellume and BinaxNOW tests require the download of a smartphone app to show results.
How accurate are these tests?
These tests report similar accuracy compared to the gold standard of PCR testing. For example, Lucira detects true positive cases 94% of the time and true negative cases 98% of the time. This means that if 100 people take the test, there will be six who will receive a positive test result when they are not infected; two people in 100 will get a negative test result even though they are infected. The other tests have similar numbers.
However, there are major caveats to these numbers. First, the accuracy is compared to PCR testing, but PCR is also an imperfect test. Second, the manufacturers derived these percentages using small sample sizes, which may limit the precision of these estimates.
This story originally appeared on: Vogue - Author:Dharushana Muthulingam
