PCR tests have been the most commonly used diagnostic tool for COVID-19 up to this point. They require skilled laboratory personnel to collect, process, and analyze the sample, and the results can be available in hours to days. Rapid antigen test results are available in as little as 15 minutes and can be done in any setting. Antigen tests work very well as a diagnostic test for people who are symptomatic or have been exposed to COVID-19 and also to screen asymptomatic people in school settings. PCR tests may also be used in these instances, but they may continue to give a positive result after someone has stopped being infectious.