"That's something that we're talking about on a daily basis," Christenson said Thursday. "I think we realize as a community as well as a community of responders that this is likely to continue for quite some time. ... We are prepared and know very well that there are individuals coming back from spring break, and we are expanding capacity to make sure that we can respond effectively and efficiently."

Christenson said expanding capacity can mean bringing in volunteers and that there are organizations keeping track of individuals who want to volunteer, as well as hiring additional staff.

The advice from Bullock on Thursday follows an advisory form the U.S. State Department telling U.S. citizens abroad to return home unless they had planned to stay in the country they were visiting for an indefinite period. The advisory also encouraged avoiding international travel.

Similarly, the State Department recommended travelers defer all cruises and anyone who has taken a cruise self-quarantine for 14 days following the trip.

While it's not fully understood how COVID-19 is transmitted, and the Centers for Disease Control and Prevention suspects people are most contagious when the most symptomatic. However, the CDC also suggests people could also be infectious without or before having symptoms.