The CDC has developed a Serology-based test for COVID-19 to assist with efforts to determine how much of the U.S. population has been infected with SARS-CoV-2, the virus that causes COVID-19. Serology tests are blood-based tests that can be used to identify whether people have been exposed to a particular pathogen by looking at their immune response.
For more information on Serology-based tests for COVID-19, please check out the Johns Hopkins Center for Health Security link below.