For the most part, the power lies in the hands of states, employers or private institutions.
Dr. Ezekiel J. Emanuel, a professor of bioethics and health policy at the University of Pennsylvania, said the United States was unlikely to make significant strides in its vaccination campaign without mandates.
“I like to say a mandate is legal, ethical and efficacious,” he said. “Ultimately, workplaces are probably going to have to.”
In his speech, Mr. Biden said his administration was not giving up on persuading people that vaccination was in their best interests, and in the interest of the country. But he made no mention of the need for states, private companies, schools and other institutions to begin requiring people who were reluctant to get vaccinated.
Jen Psaki, the White House press secretary, acknowledged in comments to reporters on Tuesday that some companies, schools and other institutions were beginning to require vaccines. But she said the administration had no intention of encouraging them to do so.
“We’re going to leave it up to them to make these decisions,” Ms. Psaki said.
But others say the administration could be more aggressive.
Lawrence O. Gostin, a professor of global health law at Georgetown University, said that even though the federal government’s authority to enact mandates was limited, the Biden administration still had considerable power to recommend them. It can provide more funding for proof-of-vaccination systems and create incentives for colleges, universities and organizations to require that a vaccine be offered, he said.
“Vaccine mandates have been very successful in the United States and globally, even in politically difficult situations, because they make becoming vaccinated the default,” Mr. Gostin said. “We have to make being unvaccinated the hard choice, not the easy one.”