Federal regulators Monday granted full approval to the Pfizer-BioNTech coronavirus vaccine — a milestone that could help increase inoculation rates and spark a wave of vaccine mandates by employers and universities amid a surge of new cases and hospitalizations fueled by the ferocious delta variant, according to two individuals with direct knowledge of the decision…

Critics for weeks had demanded that the FDA move faster on approving the vaccine, arguing that the millions of inoculations administered since late last year under an emergency authorization demonstrated the shots’ safety and effectiveness. But even as the FDA redoubled its efforts, increasing staff and computer resources dedicated to the review, the agency insisted on six months’ follow-up data for people enrolled in the pivotal clinical trial.

In the end, the vaccine approval was the fastest in the agency’s history, coming less than four months after Pfizer-BioNTech filed for licensing on May 7. The individuals with knowledge of the decision spoke on the condition of anonymity because they were not authorized to speak publicly.

“It’s been remarkably fast,” said Holly Fernandez Lynch, a bioethics expert and lawyer at the University of Pennsylvania who said careful handling of the approval was crucial to potentially persuading the “vaccine hesitant” to receive the licensed product. “You can’t have it both ways. You can’t have people saying they won’t get vaccinated until there’s full approval and then say the FDA has to hurry up” and grant that approval.