The use of PCR tests without even stating or taking into account the amount of amplified cycles used to find the genetic material, single strand of RNA in the case of covid 19, and setting the threshold above what it would take to find a live virus (37-40 vs 33) surely amplifies the cases and disregards viral load.

Most tests set the limit at 40, a few at 37. This means that you are positive for the coronavirus if the test process required up to 40 cycles, or 37, to detect the virus.

Tests with thresholds so high may detect not just live virus but also genetic fragments, leftovers from infection that pose no particular risk — akin to finding a hair in a room long after a person has left, Dr. Mina said.

The C.D.C.’s own calculations suggest that it is extremely difficult to detect any live virus in a sample above a threshold of 33 cycles.