"Polymerase chain reaction, or PCR, is a technique to make many copies of a specific DNA region in vitro (in a test tube rather than an organism). PCR relies on a thermostable DNA polymerase,…."
it is a lab tool (trick) to multiply a small sample. Kary was trying to warn people that unscrupulous "Labs" would/were using slight of hand to claim PCR could be used as a Clinical Diagnosis tool instead of the lab technique as he invented ("discovered" as Kary says).
The PCR technique was WRONGLY used by BigMed to TRICK people into thinking that they had "tested positive" for a sickness they really did not have.