By varying the sensitivity of the most commonly used Covid-19 test, the number of positive tests can be dialed up or down. From Joseph Mercola at lewrockwell.com:
From the beginning of the COVID-19 pandemic, the clarion call has been to test, test and test some more. However, right from the start, serious questions arose about the tests being used to diagnose this infection, and questions have only multiplied since then.
Positive reverse transcription polymerase chain reaction (RT-PCR) tests have been used as the justification for keeping large portions of the world locked down for the better part of 2020.
This, despite the fact that PCR tests have proven remarkably unreliable with high false result rates, and aren’t designed to be used as a diagnostic tool in the first place as they cannot distinguish between inactive viruses and “live” or reproductive ones.
Dr. Mike Yeadon, former vice president and scientific director of Pfizer, has even gone on record stating1 that false positive results from unreliable PCR tests are being used to “manufacture a ‘second wave’ based on ‘new cases,’” when in fact a second wave is highly unlikely.