Biden Seeks to Revive Vaccine Effort With New Rules and Incentives

“I think it would have a much bigger impact in parts of the country that have low vaccination rates and also get into populations that have been reluctant and hopefully show them that getting a vaccine is not problematic,” said Dr. Ezekiel J. Emanuel, a bioethicist at the University of Pennsylvania who advised Mr. Biden during his transition.

Many members of the military have been reluctant to take coronavirus vaccines. Dr. Besser said he was surprised the administration has not required them to do so sooner. Military leaders cannot require the shots because they are currently authorized on an emergency basis. Mr. Biden could order them, but has been reluctant to exercise that authority.

But Dr. Besser said Mr. Biden’s move “makes sense,” adding, “It’s highly contagious, people in the military are in very close quarters with each other, and in terms of force readiness you wouldn’t want to see Covid ripping through unvaccinated soldiers.”

Senator Mitch McConnell of Kentucky, the Republican leader and a polio survivor, encouraged people to get the vaccine. With the virus on the rise in conservative swaths of the country, Mr. McConnell is among a handful of Republican leaders who are now explicitly calling for vaccination.

“Honestly, it never occurred to me we’d have difficulty getting people to take the vaccine,” he said.

Dr. Patrick Godbey, the president of the College of American Pathologists, which is advocating for greater use of Covid-19 testing, said even before Mr. Biden spoke that the events of this week had changed the discussion. His own medical institution, in Brunswick, Ga., has not yet required workers to get vaccinated, he said.

“People are now looking at it; they are evaluating it in their own institutions, and that’s an important step forward,” he said, adding, “It’s a real line in the sand when the federal government comes out and does it.”

Jennifer Steinhauer contributed reporting.