Experts say the surplus makes sense and is not a quality-control issue. Instead, extra doses are good news regarding vaccine supply.
“That is normal, and it is intentional,” William Schaffner, MD, professor of medicine in the division of infectious diseases at the Vanderbilt University School of Medicine in Tennessee, tells Verywell. “It’s a Christmas bonus.”
Extra Doses
The FDA’s emergency use authorization (EUA) for the Pfizer COVID-19 vaccine states, “After dilution, each vial contains 5 doses of 0.3 mL per dose.” Healthcare workers and residents of long-term care facilities were among the first to receive the vaccine from the first vial shipments across the U.S. Those who were administering vaccines quickly noticed that some vials contained more than the five allotted doses.
Following these reports, the FDA issued a statement saying, “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.”
“If you get an extra dose, that’s wonderful,” Schaffner says. “If you get an extra two doses, that’s wonderful.”
But the FDA statement adds, “It is critical to note that any further remaining product that does not constitute a full dose should not be pooled from multiple vials to create one.”
A leftover half dose from one vial cannot be combined with a half dose from another vial to make a full dose. “There’s no preservative in this vaccine,” Schaffner explains. “We don’t want any chance that if you’ve gone into one vial you may have contaminated, ever so slightly, the needle. And then you would stick that contamination into the second vial.”
Why Vials Have Extra Doses
Extra solution in vaccine vials is expected, Jason Varin, PharmD, director of alumni relations at the University of Minnesota’s College of Pharmacy, tells Verywell.
“As a pharmacist who has delivered thousands of immunizations over the years—including vaccines for preventing influenza, pneumonia, and shingles, to name a few—there is almost always overfill in the vials,” he says. “That is not sloppiness on the part of the manufacturer or health provider. It is an important mechanism that ensures the appropriate number of full doses per vial.”
The intentional overfill is for unintentional medication waste that naturally occurs during the vaccination process. “It is easier to send vaccines in multi-dose vials and then drawn into individual syringes,” Ken Perry, MD, FACEP, an emergency physician in South Carolina, tells Verywell. “Doing this, however, means that a small amount of the vaccine is lost in the needle and within the vial.”
Removal of air bubbles, by tapping a syringe and spritzing out a tiny bit of medication, also causes a small amount of solution to go to the wayside, Schaffner adds. “Manufacturers, whether of drugs or of a vaccine, always take that into account,” he says.
Although Pfizer has not released a statement about the reason for the extra doses, Schaffner speculates the manufacturer might have provided more surplus solution than usual just to be sure each vial could indeed vaccinate five people against COVID-19, despite unintentional medication loss.
“As you can imagine, in something of this public scrutiny, the last thing the vaccine manufacturer wanted was for people to start saying, ‘Wait a minute, you said there were five doses, and I only got four and a half,’" he says. “They probably set the machines to overfill just so that they wouldn’t get even a single complaint that even a single vial was a little short.”
Schaffner says those who are administering the first vaccine doses available in the U.S. are likely being extra diligent with their supply. The goal in mind is to avoid too much unintentional waste of a vaccine intended to help curb a pandemic that has claimed hundreds of thousands of lives nationally and more than 1.7 million lives globally.
“As people withdrew the vaccine, this vaccine was so precious everybody was being extra careful, and they discovered, ‘Oh, look, there’s more,’” Schaffner says. “So they got an extra dose. And apparently, if you’re ultra-careful, and a bit lucky, you can actually get two extra doses out of that vial.”
In multi-dose influenza vaccine vials, Varin says an extra dose, or even more than one, is common. “The same holds true—and should—for the COVID-19 vaccine,” he says. “While I have only spoken with a few providers that have administered the Pfizer-BioNTech [vaccine] at this point, it sounds like there is pretty consistently one additional full dose or more in each vial.”
Why Were Some Extra Doses Destroyed?
Despite extra doses in multi-dose vaccine vials being the norm, the surplus in Pfizer COVID-19 vaccine vials caused a stir because the FDA’s EUA for the vaccine did not specify that extra doses could be administered. Therefore, the extra doses had to be destroyed.
“What brought a lot of attention to these extra doses was the fact that in the EUA for this vaccine, it specifically points out that each vial is to provide five doses,” Varin says. “In legal speak, that indicates that using more than five doses from a single vial is not authorized and could potentially create a situation where the provider may be in violation of the EUA.”
The FDA issued a statement about the extra doses on December 16 via Twitter to give the go-ahead for administering all obtainable full doses from each vial. The FDA later updated its Pfizer frequently asked questions page to include that information.
Extra doses could not be stored for use at a later time while vaccine administrators waited for the FDA’s guidance on what to do with the surplus. “Many [vaccines] need to be refrigerated, sometimes to very cold temperatures,” Perry says. “If the vaccine is exposed to warm temperatures for too long, it may make them no longer effective.”
The Pfizer vaccine must be shipped in thermal containers packed with dry ice. Once the vials reach their destination, they must be placed in an ultra-low temperature freezer and be kept frozen between -112 °F to -76 °F (-80 °C to -60 °C). Vials are then thawed before use, either under refrigeration, where they may be kept for up to five days or at room temperature where they can be kept for no more than two hours. Before use, vials are diluted and must be used within six hours or discarded.
“Because it has no preservative, you have to actually use all the doses in a very brief period of time,” Schaffner explains.
Now, with the FDA’s all-clear to use the extra full doses in each vial, vaccine providers can plan ahead for administering all the available jabs. “With any of these vaccines, you have to be careful in not only managing the vaccines, but you also have to manage the people who are going to get vaccinated," Schaffner says. “So if you go into a vial, you have to make sure that there are enough people in the line who are going to get all the doses.”
What the Extra Doses Mean for Vaccine Supply
The news of a dose surplus in the vials, Perry says, should offer reassurance that we will have more doses of the Pfizer vaccine than originally thought. “Extra doses of a vaccine should not lead to concern over the safety or efficacy of a vaccine,” he says.
The U.S. made an initial deal with Pfizer, signed in July, for 100 million doses of the Pfizer COVID-19 vaccine. Since the vaccine requires two doses, given 21 days apart, the deal provides enough to vaccinate 50 million people by March 2021.
Although no numbers have been released by Pfizer or the FDA, extra doses across vaccine vials could result in the ability to vaccinate millions of more people potentially earlier than planned. “This would add approximately a 20% increase in the number of vaccinations that can be provided from the Pfizer-BioNTech vials,” Varin says.
“The sooner we get the most people vaccinated the sooner we can start to resume some semblance of normalcy,” Varin says. “When the time comes for your turn, please do not hesitate to be vaccinated. As healthcare providers, we stand ready to start this process, and you should too.”
Will the U.S. Buy More Pfizer Doses?
According to Kayleigh McEnany, White House press secretary, the Trump administration is attempting to secure more Pfizer doses. “We’re hopeful that we will get an additional 100 million from Pfizer,” she said in a White House press briefing last week. “I think we will.”
However, as of the writing of this article, a new deal has not been struck between Pfizer and Operation Warp Speed. Pfizer, in the meantime, has agreements to provide vaccines to other countries. According to Duke University’s Global Health Innovator, which is mapping COVID-19 vaccine pre-purchases across the globe, key buyers of the Pfizer vaccine include the European Union, Japan, China, and the United Kingdom. Those deals could present delays for the U.S. in receiving more Pfizer vaccine doses.
In response to reports that the company was having production issues, Pfizer released a statement on December 17 refuting those claims. “This week, we have successfully shipped all 2.9 million doses that we were asked to ship by the U.S. Government to the locations specified by them,” the statement says. “We have millions more doses sitting in our warehouse but, as of now, we have not received any shipment instructions for additional doses.”
The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.
