https://www.cdc.gov/coronavirus/2019-ncov/faq.html
Q: How do you test a person for COVID-19?
A: At this time, diagnostic testing for COVID-19 can be conducted only at CDC.
State and local health departments who have identified a person under investigation (PUI) should immediately notify CDC’s Emergency Operations Center (EOC) to report the PUI and determine whether testing for COVID-19 at CDC is indicated. The EOC will assist local/state health departments to collect, store, and ship specimens appropriately to CDC, including during afterhours or on weekends/holidays.
For more information on specimen collection see CDC Information for Laboratories.