The PCR test, (polymerase chain reaction for its acronym in English), is a test used to diagnose certain infectious diseases, and also certain genetic changes. Currently the best known is RT-PCR, which is used to diagnose the Covid-19 virus.
These tests work with the detection of DNA or RNA. DNA is our genetic material, it contains all the information related to our organism. RNA is another type of genetic material, they are copies, and they influence the production of proteins. In the case of viruses that are analyzed by PCR tests, they contain some of these elements.
PCR tests are performed from a sample taken, this can be blood, saliva, mucus or tissue. They are highly sensitive, which is why they are able to detect if we are sick at a very early stage. For example, in the case of diseases that are caused by a genetic mutation, or in the case of Covid, when our viral load is still very low.