Both PCR and antigen tests have been approved by the Food and Drug Administration (FDA) and endorsed by the Centers for Disease Control and Prevention (CDC), as effective and accurate COVID-19 testing methods. Unlike antibody tests, which detect the presence of antibodies in the blood that act as evidence of a previous infection, these diagnostic tests can detect current infections caused by the COVID-19 virus.
Viral PCR tests use a fluid sample (usually taken from a nasal swab, throat swab, or a saliva sample) to check for the genetic material - in this case, the RNA - of the SARS-CoV-2 virus that causes COVID-19. These molecular tests may take longer to process than antigen tests, but are generally considered the most accurate form of viral testing available.
Antigen tests use a similar fluid sample (taken from a nasal swab or throat swab) to check for proteins in the COVID-19 virus. Rapid antigen tests may produce results more quickly than a PCR test, but also may be slightly less accurate. Specifically, antigen tests have been shown to yield occasional false-negative test results - which describes a negative test result despite current infection. Because of this, the health care providers may recommend a follow-up PCR test to definitively diagnose an active infection.
For more information about viral COVID-19 tests, testing sites, emergency-use authorizations, and more, visit the CDC's Self-Testing site here.