If there is no such law, they should make one. Quarantine them in some shelter or at home.
We do, but those laws are state laws and can not be implemented by the federal government.
Just like how Ferguson was looted and burned, and no local politician had the balls to call in the National Guard because it would end his career, same mentality was working here in the beginning.
Even if Trump asked in February for it, no governor would want to be the first, since politically, it would stink.
As they say, everyone want to get to heaven but no one wants to die.