On Jan. 31, over a month ago, the Trump administration made an excellent decision: In an effort to limit the spread of the coronavirus, it forbade most foreign nationals from entering the United States if they had recently traveled to China.

This move was immediately attacked in the language of cosmopolitan sophistication, which assumes that because travel bans and quarantines are associated with things liberals consider bad — nationalism, hardened borders, migration restrictions — they necessarily must not work as well.

But this supposed sophistication is really just a superstition. It’s certainly true that the travel ban could not, and did not, prevent the coronavirus from reaching the United States. But as with local quarantines and closings — all of which emphatically do work, whether you’re looking at the history of the Spanish flu or Hong Kong’s success combating the coronavirus today — you don’t need 100 percent effectiveness for travel restrictions to be wise and helpful. What they buy you, above all, is a slower rate of spread, and with it precious time for preparation.

So Trump made the right call, and in so doing he briefly vindicated a case that his supporters have always made for him: He acted like the guy who would make common-sensical choices in the national interest, even when they went against the nostrums of globalization and the supposed wisdom of the do-gooders.