Frustrated by the lack of testing resulting from the problem with the CDC-developed kit, the Seattle Flu Study began using an in-house developed test to look for Covid-19 in samples from people who had flu-like symptoms but who had tested negative for flu. That work — permissible because it was research — uncovered the Snohomish County teenager.
https://www.statnews.com/2020/03/03/washington-state-risks-seeing-explosion-in-coronavirus-without-dramatic-action-new-analysis-says/