Here's some interesting history on PCR.
“NYT 2007: FAITH IN QUICK TEST LEADS TO EPIDEMIC THAT WASN'T”
“...“You're in a little bit of no man's land,” with the new molecular tests, said Dr. Mark Perkins, an infectious disease specialist and chief scientific officer at the Foundation for Innovative New Diagnostics, a nonprofit foundation supported by the Bill and Melinda Gates Foundation. “All bets are off on exact performance...
“...The second was with P.C.R., the quick test to diagnose the disease, Dr. Kretsinger said.
With pertussis, she said, “there are probably 100 different P.C.R. protocols and methods being used throughout the country,” and it is unclear how often any of them are accurate. “We have had a number of outbreaks where we believe that despite the presence of P.C.R.-positive results, the disease was not pertussis,” Dr. Kretsinger added...
“The big message is that every lab is vulnerable to having false positives,” Dr. Petti said. “No single test result is absolute and that is even more important with a test result based on P.C.R.”As for Dr. Herndon, though, she now knows she is off the hook...”
https://silview.media/2020/12/26/nyt-2007-faith-in-quick-test-leads-to-epidemic-that-wasnt/
“Kerry Mullis, Nobel Prize-winning inventor of the PCR Test on Anthony Fauci”