These tests are very accurate because even if there's only a tiny amount of virus present in a patient sample,

PCR — which stands for polymerase chain reaction — is able to take genetic material from the virus, target specific gene segments that only the virus has,

and make a very large number of copies of those segments so that they can be detected and measured.

Using this method, a PCR test can tell you if you have COVID-19 right now, but not if you've had it in the past.

Although this type of test usually delivers results in four to six hours,

it's worth noting that PCR testing is very complicated and costly, and not all healthcare facilities have the ability to perform it.

Facilities that can't run this type of test may have to send patient samples to a reference laboratory and wait several days for the results.

On the other side of this spectrum, the FDA has also approved a few rapid PCR-based tests that give results in less than an hour.

At least initially, these rapid tests were reserved for triaging patients in hospitals and for testing healthcare workers.

Now that the production of these tests has ramped up further, rapid corona testing centers for the general public are starting to open in several states across the U.S.