You probably know at this point in the pandemic that if you test positive on a rapid test (and you've used the test correctly–you've got to swab pretty hard!) that the odds are overwhelming that you have COVID and are infectious. You have, no doubt, been warned that a negative result on a rapid test should be taken with a grain of salt, especially if you've been exposed to the virus or you have symptoms. And you might have heard two terms about tests thrown around: sensitivity and specificity, particularly if you've been trying to get a grip on exactly how accurate rapid tests are. As a mathematician, I think knowing a bit more about how sensitivity and specificity are calculated can help you better understand why a positive result should be headed--and a negative test should be read with some caution. The high specificity and rapid BinaxNOW antigen test turnaround time facilitate earlier isolation of infectious persons.

Donald Trump and his former White House chief of staff Mark Meadows are peddling a new story about the ex-president's coronavirus infection. Their first story was that Trump didn't test positive until Oct. 1, 2020, two days after he debated Joe Biden. Then Meadows admitted in his new book, The Chief's Chief, that Trump actually tested positive on Sept. 26, three days before the debate. That admission was problematic, since Trump never informed Biden--or hundreds of other unwitting people who interacted closely with the maskless president in the intervening five days--about the test result. So now Trump and Meadows have concocted yet another story: The Sept. 26 result was a "false positive."

Fox News Flash top headlines are here. Check out what's clicking on Foxnews.com. NEW YORK (AP) -- The NFL had 77 positive COVID-19 tests from 11 teams re-examined by a New Jersey lab after false positives, and all those tests came back negative. The league asked the New Jersey lab BioReference to investigate the results, and those 77 tests are being re-tested once more to make sure they were false positives. Among teams reporting false positives, the Minnesota Vikings said they had 12, the New York Jets 10 and the Chicago Bears nine.