Do Expired COVID Tests Work?

We’ve come to the point in the COVID-19 pandemic where you’re probably not anxious every single day about contracting the virus—the wide availability of COVID-19 vaccines and efficient therapies have thankfully made that feasible. And, with that, you certainly have some tests around your property for the just-in-case that may have been sitting there for a while. Here’s the thing, though: They can expire. Yep, there is a COVID test expiration date marked on your packaging that you may not even realize is there.

Many COVID-19 tests last for just a year or so, but the odds are strong that you’ll need to use your at some point. That may or may not be before the expiration date stamped on your package passes. So…do expired COVID tests function, or do you need to throw what you thought was a perfectly acceptable test? It’s actually a little tricky. What you should know is as follows.

Do expired COVID tests work?

Yes and no. To fully grasp that, it’s vital to clarify how COVID-19 tests receive an expiration date in the first place. “When tests are produced, the firm will assess the test over time to make sure it’s performing with the quality standards intended,” says Thomas Russo, M.D., a professor and the chief of infectious diseases at the University at Buffalo in New York. “Whatever time span they analyze it for is the expiration date that will go on that test.”

This “doesn’t always mean that the test won’t perform for a longer period of time,” Dr. Russo says—it’s only the amount of time that the test has been examined for and what is authorized or approved by the Food and Drug Administration (FDA) (FDA).

Older tests are more likely to have shorter expiration dates since there were time pressures to get tests out earlier in the epidemic, when they were first generated, and only so much time since they had been created to test how long they were good for, Dr. Russo explains. “However, firms maintained assessing the tests over time,” he explains.

As a result, “many manufacturers have secured shelf life extensions from the FDA,” says infectious disease expert Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security.

The FDA maintains a list online of permitted home COVID-19 tests, along with links to “updated expiration dates” so you may check to see if your test’s expiration date has been extended.

“If you have a test and it’s ‘expired’ based on what the packaging says, it may or may not be the most correct expiration date,” Dr. Russo explains.

What happens if you utilize an expired test?

Again, the expiration dates are a reflection of how long the firm that made the test discovered that it was good for—or the period of time in which they were able to assess the test. With that, there’s a chance that your test will still be good after the expiration date mentioned. “Most tests will still perform past their expiration date for several weeks,” Dr. Adalja notes.

If the test has genuinely expired “you are more likely to obtain a false negative,” says Jamie Alan, Ph.D., associate professor of pharmacology and toxicology at Michigan State University. “The test can be negative because the reagents or ‘ingredients’ are past their shelf life and are not operating as they should,” she explains. “They are likely good past their expiration date, although how long I cannot say with any degree of certainty.”

You have symptoms of COVID-19 and the only test you have at home is expired, Alan suggests you could try it. “If you receive a positive, you are probably positive,” she explains. “If you get a negative, it would be wise to follow up with another test, perhaps a PCR test or another rapid at-home test.”

Why do COVID tests expire?

COVID tests contain specific reagents (called components) that react with the virus, or lack thereof, from your swab, Alan explains. “These ingredients do not work forever,” she explains. “This is true for pharmaceuticals, lab supplies, and food.”

How do I know if my BinaxNOW is expired?

BinaxNOW is one of the most common home tests out there, and it normally includes an expiration date stamped on the back of the box. But, again, that may not be the most up-to-date expiration date for your test.

If you have a test with an expired date on the package, check out the FDA’s list of updated expiration dates for BinaxNOW tests to see if it’s been extended. Just bear in mind that you’ll need to have your box’s lot number available.

But, if your test is expired—both on the box and per the FDA’s new dating—and you want to be sure you’re getting an accurate reading, Dr. Russo says it’s “probably preferable to not take that test.”

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