Musk questions accuracy of rapid coronavirus antigen tests

• "Something extremely bogus is going on. Was tested for covid four times today. Two tests came back negative, two came back positive. Same machine, same test, same nurse. Rapid antigen test from BD," Elon Musk wrote on Twitter, likely referring to Becton Dickinson's (NYSE:BDX) rapid antigen test.
• Back in September, Becton Dickinson said it was investigating reports from U.S. nursing homes that its rapid coronavirus testing equipment was producing false-positive results, but did not respond to a request for comment following the latest news.
• The FDA has also issued a letter to alert clinical laboratory staff and health care providers that false positive results can occur with antigen tests.
• "For example, a test with 98% specificity would have a positive predictive value (true positives) of just over 80% in a population with 10% prevalence, meaning 20 out of 100 positive results would be false positives."
• "The same test would only have a PPV of approximately 30% in a population with 1% prevalence, meaning 70 out of 100 positive results would be false positives. This means that, in a population with 1% prevalence, only 30% of individuals with positive test results actually have the disease."
• "At 0.1% prevalence, the PPV would only be 4%, meaning that 96 out of 100 positive results would be false positives."
• https://seekingalpha.com/news/3635981-musk-questions-accuracy-of-rapid-coronavirus-antigen-tests