![]() Still relevant?Īs the covid-19 pandemic spread around the globe last year, economists and scientists called for massive expansion of testing and contact tracing in the US, to find and isolate infected people. If used at scale to screen for covid, they could send millions of anxious people in search of lab tests and medical care they don’t need. Related StoryĪs a result, I don’t think home tests are as useful as some have hoped. This lower background rate means if home tests were used by everyone in the country tomorrow, there could be five to 15 wrong positives for every right one. ![]() Now consider this same phenomenon-a higher chance of false positives than of real ones-applying to a large group, or even a whole country. The way I was using the test, any positive result was nearly certain to be wrong. What this meant is that my chance of a correct positive when I took the test was also essentially zero, while my false positive chance remained 2% like everyone else’s. The second source of trouble I didn’t anticipate is what is known as “pretest probability.” As I said, I don’t socialize, so my probability of actually having covid in first place was very low, maybe even zero. By the time my review of the home tests was complete, I’d tested five times in two days, accumulating 1 in 10 odds of being told I had covid when I didn’t (a 2% chance of a false positive each time, multiplied by five tests). The first way is through repeat testing, the kind I did. What I didn’t realize-and what your everyday CVS shopper won’t either-is that there are two ways that less-than-perfect specificity can get amplified into a bigger problem. For the home tests I tried, that figure is about 98%, with a corresponding 2% rate of false positives. The tricky part of unrestricted testing, I learned, comes instead from the concept of “specificity,” or the rate at which a test correctly identifies negatives. But if the alternative is no test at all, then none of those infections would be caught. That is, they catch about nine of every 10 infections, a metric called the test’s “sensitivity.” Some people have said that any missed cases are a worry, since a person with a false negative could go out and infect someone else. For example, tests with printed "October 2022" expiration dates should be considered appropriate for usage until October 2023.The issue with home tests is accuracy, which is between 85% and 95% for detecting covid. The tests are good for an additional year past their expiration dates. The Flowflex COVID-19 Antigen Home Test from Acon Laboratories can also be used well past its printed expiration date, according to the FDA, which granted the extension in March. Abbott added that expiration dates could be extended again in the future, pending new data on their viability. "All BinaxNOW COVID-19 Antigen Self Test kits currently have a twenty-two-month expiry date," the company said. In January of 2023, the pharmaceutical firm told customers that kits they'd previously purchased "may now have a longer than labeled product expiry date." To see if a BinaxNOW COVID-19 Antigen Self Test kit in your possession has a new epiration date, you can search for its lot number in the attached list here. ![]() Which test brands can you use after they've "expired"?Ībbott's widely used BinaxNow COVID-19 test kits now have a shelf life of up to 22 months, depending on when the tests were manufactured. See the FDA's full list of test-kit expiration date extensions here. Here's how to find out if your COVID-19 test is safe to use. ![]() If you still have any older tests stored away, the good news is that some COVID-19 test kits that are past their expiration dates may still be effective. ![]() Can you still get free COVID tests in 2023? Here's what to know about your options.The government will once again offer free rapid at-home tests by mail, which you can order online at starting Monday, Sept. It's also still possible for both insured and uninsured people to get free testing. Once in short supply, test kits are now easier to come by, but they can be costly in stores, roughly $25 for a pack of two tests. Yet different COVID-19 tests bear expiration dates on their packaging that have long since passed, raising questions about whether they're still effective. Many people still have kits the government formerly provided to all households for free, especially as some schools and businesses again require tests. With COVID-19 cases on the rise again in the U.S., Americans are reviving a familiar precautionary measure: Screening for the virus using rapid at-home tests. Are expired at-home COVID tests still effective? Here's how to tell. ![]()
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