The Food and Drug Administration granted full approval to Pfizer-BioNTech's two-dose vaccine Monday for people ages 16 and up, making it the first Covid-19 vaccine to pass this final regulatory hurdle.

"The FDA's approval of this vaccine is a milestone as we continue to battle the Covid-19 pandemic," Acting FDA Commissioner Dr. Janet Woodcock said in a statement. “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. Today’s milestone puts us one step closer to altering the course of this pandemic in the U.S.”

Full approval may help persuade some vaccine-hesitant people to get vaccinated. A Kaiser Family Foundation survey from June found that 3 in 10 unvaccinated adults would be more likely to get the shots if a vaccine were fully approved.

The FDA's decision may also pave the way for more vaccination mandates: Many businesses were waiting for full approval before they required employees to be vaccinated.

"Full approval could not come at a more important time, as the highly contagious delta variant continues to drive up caseloads and deaths across the U.S.," the president and CEO of the Robert Wood Johnson Foundation, Dr. Richard Besser, former acting director of the Centers for Disease Control and Prevention, said in a statement. "I am hopeful that full approval will address any remaining concerns and will move many people to a 'yes' on vaccination."

Still, Besser said the lack of vaccines in middle- and low-income countries "represents a global failure," adding, "Ensuring an adequate supply of vaccines in every country and community must be a health, economic, and moral imperative for the world."

Last week, federal health officials announced that, starting Sept. 20, people who received the Pfizer vaccine will be eligible for third doses eight months after their second doses. The FDA has not yet signed off a third dose, however.

No Covid vaccines have been authorized or approved for use in children under 12.

Pfizer's vaccine is one of three in use in the U.S. Moderna has also applied for full approval, also known as a Biologics Licensing Application. Johnson & Johnson has not yet applied for full approval, and remains in use under emergency authorization.

Pfizer's product was the first Covid vaccine to gain emergency use authorization, in December. As of Monday, more than 203 million doses have been given in the U.S., according to the CDC.