2014: the [PCR] method is so sensitive that it can detect a single genetic molecule of this virus. For example, if such a pathogen scurrys over the nasal mucosa in a nurse for a day without falling ill or noticing anything else, then she is suddenly a Mers case. Where previously fatally ill people were reported, mild cases and people who are actually core healthy are now suddenly included in the reporting statistics.
— Read on amp2.wiwo.de/technologie/forschung/virologe-drosten-im-gespraech-2014-der-koerper-wirdstaendig-von-viren-angegriffen/9903228.html

Very sensible. PCR testing is a bad idea for diagnostics. Yet, fast forward 6 years, and Drosten is responsible for the paper that formed the basis for the worldwide mass testing policy for Covid19.

What changed? Certainly not the science or the tests. After all, use of PCR has been widely criticised by many scientists (no, not on the MSM). And recently a damning review of the above paper appeared.