As the government sends out another round of free COVID-19 tests, some appear to have arrived already expired.
That doesn’t mean you can’t use them: The Food and Drug Administration (FDA) has extended the expiration dates of many tests after collecting additional data from manufacturers showing that their tests are still effective.
“It’s important to know that you can trust the accuracy of these Covid tests,” said Courtney Lias, director of the office that reviews in vitro diagnostics at the FDA.
How does the FDA confirm that the tests still work?
Test kit manufacturers were eager to get to market as quickly as possible at the height of the pandemic, so they submitted their products to the FDA with expiration dates that were only around six months. But in the years since, manufacturers have conducted additional evaluations to confirm that the tests work over a longer period of time. The FDA has approved extensions of these tests on an ongoing basis, sometimes up to a year or two after the initial expiration date.
To get an extension of the expiration date, “these companies are forced to literally put their product on a shelf and wait,” said Nathaniel Hafer, associate professor of Molecular Medicine at the University of Massachusetts Chan School of Medicine.
For example, Acon Labs, which makes Flowflex tests for home use, evaluated batches of old tests every three months to make sure they were still working, said Michael Lynch, the company’s vice president of sales and marketing. Acon Labs added inactivated virus particles to the mucus of volunteers and used those samples to confirm that the tests were still giving accurate results.
You can check if your test is actually expired by looking at the lot number and checking it against this list from the FDA.
The FDA is also making sure that covid tests work against the variants currently circulating. The tests remain effective because they detect a part of the virus that has not changed, even if new variants have evolved, said Peter Chin-Hong, an infectious disease specialist at the University of California, San Francisco campus. The FDA estimates that home tests detect the virus in at least 80 percent of infection cases.
What happens if my test is actually expired?
Both the liquid that comes in the dropper with the Covid tests and the test strips themselves can degrade over time, Chin-Hong said. This means that if the test’s expiration date has not been extended, you should not use it after that period; otherwise, you risk getting a false result.
Tests can also be damaged if exposed to extreme heat.
“If you have it sitting in direct sunlight on the dashboard of your car for months or weeks, I probably wouldn’t feel comfortable with it, regardless of what the expiration date is,” Chin-Hong said.
You should always make sure that the control line—which usually appears next to the “C”—is visible when using a rapid test to make sure it works.
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