Pharmacists discovered that the Pfizer vials, which are supposed to contain five doses, may have enough of the vaccine to administer six or seven. The FDA has advised that those extra doses may be used.
"At this time, given the public health emergency, FDA is advising 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," a representative for the agency told The Washington Post.
Politico was the first to report the news.
Pharmacists nationwide noted the extra supply of vaccines and reached out to Pfizer for guidance, but many threw away hundreds of extra doses since vaccinations began on Monday, as FDA guidelines dictated there were five doses.
The FDA did not immediately publicly announce the guidance and Pfizer learned of the change on Wednesday afternoon, according to Politico.
The extra doses may increase the supply of remaining vaccines by up to 40%.
"The amount of vaccine remaining in the multidose vial after removal of five doses can vary, depending on the type of needles and syringes used," Pfizer spokeswoman Sharon Castillo said. "At this time, we cannot provide a recommendation on the use of the remaining amount of vaccine from each vial. Vaccinators need to consult their institution's policies for the use of multidose vials."
Both the FDA and Pfizer said that leftover vaccines from multiple vials should not be mixed due to risk of contamination.
The news of the additional doses came as the federal government has been engaged in negotiations with Pfizer to ramp up production for the second quarter of 2021.
"We are working with them to provide them whatever assistance, now that they have identified some of the production challenges," Health and Human Services Secretary Alex Azar said Wednesday, adding he was "very optimistic" about the talks.