The U.S. gave full approval for use of the Covid-19 vaccine from Pfizer Inc. and partner BioNTech SE Monday, a move quickly followed by announcements from the Pentagon, the New York City school district and others that they would begin requiring vaccinations.

The Food and Drug Administration’s approval was seen by public health officials as a key step to convince hesitant individuals to get the shot and to encourage employers to mandate it.

“Today I’m calling on more companies in the private sector to step up with vaccine requirements that will reach millions more people,” President Biden said. “I call on you to do that—require it.”

The Pfizer-BioNTech vaccine was cleared by regulators last year on an emergency-use basis, as were subsequent clearances for Moderna Inc. and Johnson & Johnson vaccines.