Victoria, Australia has done maybe 5-15k tests per day and had zero cases in I think 61 days now. They do get false positives, about one in ten or twenty thous

Victoria, Australia has done maybe 5-15k tests per day and had zero cases in I think 61 days now. They do get false positives, about one in ten or twenty thousand it seems, but most of them had the virus at some point in the past and the test was still detecting dead virus fragments, so the "completely false" positive rate is even lower. The false positives are re- tested, and it's almost always concluded that they're false. Hence 61 days with no cases - any false positives in that time have been identified as such, so the process taken as a whole has a very low false positive rate indeed. But even the raw "one in 10k" false positive rate they see is low enough that almost all positive tests anywhere with an active COVID outbreak are true positives.