Your questions, answered "I bought several covid test kits and they have a March 2022 expiration date. Can they be relied on past March 31, 2022?" – Esther in Virginia It depends. In general, both the Food and Drug Administration and most test manufacturers agree that you should use an at-home rapid test before the expiration date printed on the box. That is the latest date that the company can guarantee that the tests will work as expected. However, there are exceptions. The manufacturers of at-home tests are monitoring the stability of their test kits and some have asked the FDA to extend the authorized expiration dates as new data from company studies show the tests can last longer than originally printed on the box. Tests that last longer allow people to stock up ahead of potential surges. The FDA has granted two test brands extensions allowing them to stretch the expiration dates printed on the box. iHealth Labs's Covid-19 Antigen Rapid Tests: The FDA on Tuesday extended the shelf-life of iHealth home test kits from six to nine months. "If the expiration date printed on your box says 2022-05-21, the updated expiration date is 2022-08-21," spokeswoman Sharon Fei said in an email. You can look up the new expiration date of your test by entering the lot number on the iHealth Labs website. "We will continue to apply to FDA for shelf-life extensions every three months based on our stability studies, and the new shelf-lives for our tests will apply to tests already produced as well as future production," the company said in a statement. Access Bio, Inc.'s CareStart Covid-19 Antigen Home Test: These tests last for three months longer than listed on the box, after the FDA extended the shelf-life to nine months. Boxes marked to expire in March will be good until the end of June. Those marked to expire in April will last through July. And boxes marked to expire in May can be used through August. If you're unsure whether your home covid test is expired, you should contact the manufacturer. All of the rapid tests on the market will eventually expire and could produce an inaccurate result because the solutions used to detect antigens can become less effective over time. But there may be some wiggle room if your test has very recently expired, says Wilbur Lam, a physician and biomedical engineer at Emory University. He runs a lab tasked by the National Institutes of Health with evaluating the performance of the rapid tests on the market. "The best way to think about this is kind of similar to sell-by dates on food," Lam said. "Your carton of milk has a sell-by date, but is there any magical thing that happens on that day? No." As more time passes, it is more likely that the test will not work properly. "It's a judgement call," he added. | 
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