The U.S. gave full approval to Pfizer’s COVID-19 vaccine Monday, a milestone that may help lift public confidence in the shots as the nation battles the most contagious coronavirus mutant yet.

The vaccine made by Pfizer and its partner BioNTech now carries the strongest endorsement from the Food and Drug Administration, which has never before had so much evidence to judge a shot’s safety. More than 200 million Pfizer doses already have been administered in the U.S. — and hundreds of millions more worldwide — since emergency use began in December.

“The public can be very confident that this vaccine meets the high standards for safety, effectiveness and manufacturing quality the FDA requires of an approved product,” said acting FDA Commissioner Janet Woodcock. “Today’s milestone puts us one step closer to altering the course of this pandemic in the U.S.”

The U.S. becomes the first country to fully approve the shot, according to Pfizer, and CEO Albert Bourla said in a statement he hoped the decision “will help increase confidence in our vaccine, as vaccination remains the best tool we have to help protect lives.”