Now, the amiable academic faces a real-world test of his pithy TV advice: If the government fails to secure enough vaccines and tests, forcing Americans into long waits, it’s his problem. If a new variant causes a sixth pandemic wave, or besieged hospitals cannot handle an avalanche of cases, those are his problems, too, and ones that can’t be explained away in a cable-news segment.

The longtime physician has admitted to friends that he’s never faced challenges like running a White House team and navigating the bitter partisanship that animates the nation’s capital. But his defenders say he’s more than well-equipped.