With many Americans still unvaccinated and the delta variant sparking a sharp rise in coronavirus cases, the Food and Drug Administration is under growing pressure to grant full approval to coronavirus vaccines being used under the agency’s emergency authority.

Some lawmakers and health care experts pushing for quick approvals note that the shots — particularly the highly effective mRNA vaccines by Pfizer-BioNTech and Moderna — have been administered to tens of millions of people in the United States and worldwide without significant problems. They argue that universities, governments and employers would feel more comfortable imposing vaccine mandates after full approvals, and predict some people would be more willing to get the shots.

Pfizer and BioNTech submitted their request for full approval, called a biologics license application, on May 7, and Moderna began a rolling submission in June. Johnson & Johnson has said it will submit its application later this year. Typically, it takes the agency at least several months to grant a full approval for a vaccine. But some officials have said that the Pfizer vaccine could be approved by late summer or early fall.

In an interview Friday, Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, which regulates vaccines, said the agency is pursuing “an all hands-on-deck” strategy to accelerate an already expedited effort to grant full approval to the Pfizer-BioNTech vaccine. He said the agency was essentially “in a sprint” to complete the process.

He also discussed the differences between emergency use authorizations, which are temporary clearances for public health emergencies, and full approvals, which remain in effect indefinitely unless a problem with a vaccine emerges.