On August 23, 2021, the Food and Drug Administration (FDA) fully approves the Pfizer-BioNTech COVID-19 vaccine for people aged 16 and older, following a manufacturing review and analysis of the company’s expanded clinical trial, which included approximately 44,000 participants and found the vaccine to be 91 percent effective in preventing COVID-19. The Pfizer-BioNTech vaccine was the first COVID-19 vaccination to receive full review and approval from the U.S. regulatory agency. (FDA approval for the vaccine’s use in children aged 5 through 11 followed in October 2021.) Previously, in December 2020, the Pfizer-BioNTech vaccine was granted emergency use authorization by the FDA in response to the public health emergency posed by the coronavirus pandemic. That authorization involved a review of safety data on over 37,000 participants in a randomized, placebo-controlled study. “While millions of people have already safely received COVID-19 vaccines, we recognize that for some, the FDA approval of a vaccine may now instill additional confidence to get vaccinated,” said Dr. Janet Woodcock, the then acting FDA Commissioner. “Today’s milestone puts us one step closer to altering the course of this pandemic in the U.S.” The FDA’s approval came amidst the spread of the highly contagious COVID-19 delta variant across the country. It also represented a turning point in U.S.’s response to COVID-19, as more private and public entities began instating vaccination requirements to stem the spread of COVID-19. Among those who adopted vaccine mandates for employees in the wake of the Pfizer-BioNTech vaccine’s FDA approval were the Pentagon and the New York City school system.