Corona Virus: Fortunately Hawaii Lost Case Against Trump
Volokh: … Yesterday, President Trump issued a travel ban from the twenty-six European nations that make up the "Schengen Area." ....
The Proclamation relied on 8 U.S.C. 1182(f). The Supreme Court considered this provision in Trump v. Hawaii. Chief Justice Roberts's decision (rejecting Hawaii’s arguments) opined on the risk of epidemics.
You can hear Roberts's announcement from the bench (via Oyez):
“…commonsense and historical practice confirm that the provision does not limit the President's authority under Section 1182 to determine who may enter the country. In response to diplomatic disputes both President Carter and President Reagan broadly suspended entry on the basis of nationality. And on plaintiffs' reading the President would not be able to suspend entry from a particular country in the event of an epidemic in that country or even if the United States were on the brink of war with that country. In sum, the proclamation is squarely within the scope of the President's authority under the INA." ….
read … The European "Schengen Area" Travel Ban and Trump v. Hawaii