A PCR (polymerase chain reaction) test is a type of molecular test that often requires a patient sample to be sent to a lab for analysis. Getting results can take anywhere from several hours to days after being received at the lab. A PCR test can sense low levels of viral genetic material (e.g., RNA), so these tests are usually highly sensitive, which means they are good at detecting a true positive result.
An antigen test, or rapid antigen test, detects viral proteins and provides results in less than an hour. Antigen tests tend to be less sensitive than molecular tests, but you are able to get results more quickly.
You may purchase your own antigen test or PCR test to perform yourself at home. The at-home PCR test sample has to be mailed to a lab for analysis.