Unlike direct detection methods such as PCR or antigen detection tests that detect acutely infected persons, antibody tests help determine whether the individual was previously infected. Serologic assays do not replace direct detection methods as the primary tool for diagnosing active SARS-CoV-2 infections, however they do have important applications in monitoring and responding to the COVID-19 pandemic. Although serologic tests should not be used at present to determine if an individual is immune, the tests can help determine the proportion of a population previously infected, and the degree to which they may have a level of immunity.