While antigen tests look for proteins on the surface of the virus to ascertain the presence of the pathogen, PCR (polymerase chain reaction) tests are engineered to seek genetic material called RNA that instructs the virus to make these proteins.
Both tests also require a swab from the back of your nose or throat as a sample and cannot determine whether you are contagious if positive but that’s where the similarities end.
In the case of PCR, the sample is sent to a lab where it is heated and cooled using special reagents to convert the virus’s RNA into DNA, and then make millions of copies of the DNA, which allows for the identification of the organism. This process can take hours, requires sophisticated lab equipment and technicians, and is typically done one sample at a time, although there are machines that can process multiple samples. Although the sample needs to be sent to a lab, the time consuming process delivers as the results are almost 100% accurate in spotting infected people when there is virus on the swab.