The United States has more COVID-19 vaccines than initially thought.

The Food and Drug Administration announced the news Wednesday, after multiple hospital pharmacists reported leftover doses in vials containing the Pfizer-BioNTech vaccine. The vials were reportedly intended to hold only five doses, but as reported by Politico, health workers noticed some of the vials contained up to six or seven doses—a confusing finding that led some pharmacists to throw out the extra dosages. 

Shortly after Politco's report, the FDA took to Twitter to advise "that it is acceptable to use every full dose obtainable (the sixth, or possibly even a seventh) from each vial, pending resolution of the issue." According to the outlet, the extra vaccine could increase the nation's supply by up to 40 percent. The government reported an initial delivery of 2.9 million doses across the US this week, but the recent discovery of extra doses suggest that number may be closer to 4 million.

Though the FDA insists it's perfectly fine to use the extra doses within a vial, it says leftover vaccine from different vials should not be mixed because of the risk of contamination. 

Ahead of the vaccine's distribution, Pfizer confirmed it had produced 25 million doses of the vaccine to be administered before the year's end. That would be enough for 12.5 million Americans, as the vaccine requires two doses three weeks apart. 

Meanwhile, Pfizer's CEO, Albert Bourla, told CNBC that he has yet to receive the vaccine, and that he and the other Pfizer executives will not “cut the line.”