RELATED: Dr. Fauci Just Issued This New Warning to All Americans—Vaccinated or Not. As cases increase again, virus experts are once again stressing the importance of testing yourself for COVID at home. “If you are going to be around the vulnerable population that can’t be protected from the disease–and, unfortunately, we have a lot of people that fall into that category—then you should do everything in your power to try and make sure you don’t have the virus,” Omai Garner, PhD, director of clinical microbiology in the UCLA Health System, told NPR. A recent study from Michigan evaluating the impact of at-home COVID tests found that they’re extremely important throughout spikes. According to this study, infection rates during one of the recent variant surges was significantly lower in cities that received free at-home tests from the state than those that had not. “It’s clear that at-home rapid antigen tests are useful, and they have tremendous value at an individual level in terms of how people decide to live their lives in the pandemic, but also provide invaluable information to experts at a population health level,” Apurv Soni, MD, an assistant professor of medicine and principal investigator of the study, said in a statement, adding that people should “know to use them when cases are rising, and not to use them when COVID-19 cases are low.” It’s likely that many of us still have COVID tests stored away at home, whether you stockpiled too much during the winter Omicron surge or you haven’t used all of the ones delivered by the U.S. Postal Service (USPS). If that’s the case, you can and should use these to start testing yourself again amid rising infections—even if they say they’re expired. William Schaffner, MD, a virus expert and professor in the Division of Infectious Diseases at Vanderbilt University Medical Center, recently told CNN that at-home COVID tests are manufactured to last longer than one might expect. “We have tests now that have been shown to be good for a year and I think some probably even longer. In other words, these are very, very stable tests,” he explained. The expiration dates are there for a reason, but you have some wiggle room. “Now, if I have a test that expired last week, will it still be accurate this week if I use it? And the short answer is yes,” Schaffner said. “As long as you haven’t abused the test in some way, put it in a deep freeze or left it out in the sun or something like that. Sure. We can rely on the results of the test.” Other experts have even green-lit expired tests for longer than that. “My expectation is that most of them, if not all of them, eventually will have a two-year expiration date at least. If the control line is showing up and it’s within 18 to 24 months of the manufacture date, you should assume the test is working,” Michael Mina, PhD, an home-test technology expert and chief science officer for eMed, told The New York Times. RELATED: For more up-to-date information, sign up for our daily newsletter. All COVID tests should be marked with a manufacturing date and an expiration date, according to The New York Times. On its website, the U.S. Food and Drug Administration (FDA) says it “does not recommend” using at-home COVID tests beyond their authorized expiration dates. “COVID-19 tests and parts they are made of may degrade, or break down, over time. Because of this, expired test kits could give inaccurate test results,” the FDA warns. But according to Schaffner, the agency has been extending its authorized expiration dates on certain tests over time. “Since it takes time for test manufacturers to perform stability testing, the FDA typically authorizes at-home COVID-19 tests with an expiration date of about four to six months from the day the test was manufactured, based on initial study results,” he explained. “Once the test manufacturer has more stability testing results, such as 12 or 18 months, the test manufacturer can contact the FDA to request that the FDA authorize a longer expiration date.” If this happens, the FDA says you could receive an alert from your test’s manufacturer—although this isn’t always the case. “When a longer expiration date is authorized, the test manufacturer may send a notice to customers to provide the new authorized expiration date, so the customers know how long they can use the tests they already have,” Schaffner added. Due to the continuous testing, the expiration dates on some at-home COVID tests might not be accurate to how long they can actually last, Schaffner explained to CNN. “So you could have gotten a test from the same manufacturer and a shorter and a longer expiration date, depending upon when the actual test was made and delivered to the store or sent to you by the federal government,” he said.ae0fcc31ae342fd3a1346ebb1f342fcb According to The New York Times, this might be the case for owners of BinaxNOW tests. The FDA extended the shelf life of this test from 12 months to 15 months in Jan. 2022, meaning many consumers should add another three months to the expiration date listed on their box. An FDA spokesperson told the newspaper that anyone with a question about their specific test’s expiration should look at the agency’s website for any authorization documents indicating an extended shelf life. “Many people now have a small inventory of tests at home,” Mara Aspinall, an expert in biomedical diagnostics at Arizona State University, told The New York Times. “It would be a pity if somebody has symptoms, but they don’t use a test because it’s a few days out of date. If a test is days out of date, it’s highly likely it’s still effective. If it’s months out of date, it’s very important to check the website to see if the date was extended.” RELATED: Dr. Fauci Warns That Vaccinated People “Need to Realize” This Now.