what temp does the vaccine need to be kept at

The Pfizer COVID-nineteen vaccine needs to be stored at minus seventy Celsius. Health care providers volition need to store information technology either in dry ice for shorter stints or in specialized freezers. Leon Neal/Getty Images hide caption

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Leon Neal/Getty Images

The Pfizer COVID-19 vaccine needs to be stored at minus 70 Celsius. Health care providers will need to store it either in dry ice for shorter stints or in specialized freezers.

Leon Neal/Getty Images

Updated 11:55 a.grand. ET

Two drugmakers, Pfizer and Moderna, have announced promising interim results for their vaccine candidates, raising hopes in the U.South. and abroad that the end of the pandemic may be in sight. But, if and when the vaccines are authorized by the Food and Drug Administration, distributing them presents a daunting challenge.

One big reason? 1 of the front-runners in the vaccine race — the one made by Pfizer — needs to be kept extremely common cold: minus seventy degrees Celsius, which is colder than winter in Antarctica. Moderna has said that its vaccine needs to exist frozen too, just only at minus 20 Celsius, more like a regular freezer.

Since there will be limited vaccine doses at commencement, immunization managers across the country will need to have plans to distribute any and all vaccine doses that are available. For months, they've been puzzling over the detail challenges presented by the Pfizer vaccine, which requires these ultra-cold conditions.

"I believe it can be done," says Debra Kristensen, a thirty-year veteran of vaccine innovation and supply chains at PATH, an international nonprofit focused on public health. "Ebola vaccine, for case, was successfully used in a few African countries and also required this ultra-cold concatenation storage."

Distributing vaccines in these conditions "is possible, but it'southward definitely going to be much more expensive and more difficult," she says. Pfizer has tried to calm concerns nearly the challenges presented by these cold temperatures. It has designed its ain packaging to go on doses super cold with dry ice, so that they tin exist stored for a few weeks without specialized freezers (the packaging has been informally nicknamed "the pizza box").

Moderna's vaccine, Kristensen explains, "can be distributed in more of a standard fashion — health workers are used to information technology, facilities are used to information technology — it's more normal."

Hither'south some background on why these vaccines need to be kept so cold — and how they differ.

Why the deep freeze? Remember about M&Ms

To sympathise why these vaccines need to exist frozen, it helps to understand a bit about how they work.

Both the Moderna and Pfizer vaccine candidates use a new approach to unlock the body's allowed defenses. The approach uses messenger RNA, or mRNA, to turn a patient'southward cells into factories that make 1 particular coronavirus protein.

That poly peptide kicks off an immune response as if there was a real coronavirus infection (to be articulate, since it's simply one virus protein, there'southward no mode the vaccine could actually infect someone or make them sick with COVID-19). Then, if someone who was immunized gets exposed to the coronavirus later, their body's immune system volition be able to fight it off more easily and they're more probable to avoid serious affliction.

It's a vaccine engineering science that'due south so new, no mRNA vaccines have ever been canonical past the Food and Drug Administration.

Vaccines fabricated from mRNA can be made much faster than older vaccines could, explains Margaret Liu, a vaccine researcher who chairs the board of the International Guild for Vaccines and specializes in genetic vaccines. The problem, says Liu, is that mRNA is "really hands destroyed, and that's because there are many, many enzymes that will just break it apart."

Here'due south an analogy: Think of the vaccine every bit a chocolate bar that melts easily. Just equally at that place are means to keep the chocolate from melting into goo, there are things the drugmakers did to protect their COVID-19 vaccines.

The first step, Liu says, was to modify the mRNA nucleosides — the "building blocks" of the RNA vaccine. "They've used modified versions because those are more than stable," she says. This would be like irresolute the chocolate recipe then information technology'southward non quite so melty.

The adjacent step was to utilise lipid nanoparticles, which, Liu explains, "is kind of like putting your chocolate within a processed coating — you have an 1000&One thousand, so the chocolate doesn't melt."

But even with the stabilized building blocks and lipid coating, the mRNA could still autumn apart easily, which is why the vaccine is frozen.

"Everything happens more slowly as yous lower the temperature," Liu says. "So your chemic reactions — the enzymes that break down RNA — are going to happen more slowly." Information technology's the same idea as freezing food to go on it from spoiling.

Because the specific formulations are underground, Liu says, it's not clear exactly why these two mRNA vaccines have different temperature requirements.

"It but comes down to what their data is," she says of Moderna's vaccine. "If their data shows that it's more stable at a sure temperature, that's it."

Moderna spokesperson Colleen Hussey explained to NPR in an email that its vaccine doesn't need to be kept so cold because of its particular "lipid nanoparticle properties and structure," and because the company has learned from experience — information technology's developed 10 mRNA vaccine candidates already. "Now we don't need [ultra-cold weather] every bit the quality of product has improved and [it] doesn't need to exist highly frozen to avoid mRNA degradation," Hussey explained.

"Stress testing" to tease out these temperatures

It's possible that Pfizer's vaccine could eventually exist shown to be stable in somewhat warmer conditions — or for longer times out of the freezer.

To figure out a vaccine'due south temperature requirements, drugmakers practise extensive, time-consuming thermostability studies.

That research involves keeping the vaccine "at other temperatures to see how much you tin stress the arrangement," explains Liu. She says you would outset at ultra-cold temperatures, then try regular freezer temperature, and so refrigerator temperature, and finally room temperature.

You might too put the vaccine at fluctuating temperatures "to sort of mimic what would happen if [a vaccine shipment] got left on a loading dock and something went wrong," Liu says.

Then drugmakers accept to clarify the vaccine samples that have been put through all that and do tests (usually in mice) to see if the vaccine yet works the way it's supposed to.

All of this is measured in real time. "If a vaccine has a ii-year shelf life at refrigerator temperatures, then the manufacturer really needs to put the vaccine at that refrigerated temperature for two years and meet if at the finish the product is still constructive," Kristensen explains. "Given the urgent demand for these COVID-xix vaccines, manufacturers will likely begin releasing them with shorter shelf lives and then they'll expand the shelf life durations as they get together more than data."

Pfizer spokesperson Jerica Pitts told NPR "in that location are ongoing studies on this front end," but did not reply whether any imminent changes to the temperature requirements might be coming as a result of those studies.

"I dubiousness that [Pfizer] will be able to move away from the ultra-cold weather during initial transport and storage," says Kristensen. "Merely if they can prove that the vaccine tin can be kept at refrigerated temperatures for some time later existence removed from frozen storage, that helps facilitate distribution and assistants out to more remote areas and to specific groups of people."

Temperature requirements call for dissimilar distribution plans

Right now, Pfizer says its vaccine needs to exist kept at minus 70 degrees Celsius and can last in a specialty freezer for upwardly to six months. The specialty shippers can hold upwardly to 5 "pizza box" trays of vials and exist refreshed with dry ice every five days for up to 15 days to keep the vaccine at the right frozen temperature.

Fifty-fifty that presents challenges, though — a Pfizer scientist told a CDC advisory council in Baronial that information technology's non supposed to exist opened more than twice a day and needs to be closed within 1 minute of opening. Once it'southward thawed, the vaccine can be refrigerated for 5 days.

Moderna says its vaccine candidate is stable at regular freezer temperature — minus 20 degrees Celsius — for upwardly to six months, and after thawing it tin can last in the refrigerator for 30 days. It can also be kept at room temperature for up to 12 hours. This, explains Kristensen, is useful for health care workers in the field, "considering now the vaccine doesn't need to get in and out of the refrigerator each time it's administered."

Given the demand, if both Pfizer and Moderna's vaccines are authorized effectually the aforementioned time, states volition figure out how to use both in different settings.

Christine Finley, the immunization director in Vermont finalizing that state'south distribution plan, says it makes sense to call back almost distributing Pfizer'due south vaccine to larger population centers, not simply because of its temperature, but because the smallest amount yous tin can guild is 975 doses (usually information technology's more similar 100 doses or fewer).

"[If] yous have a large university where you're going to be able to reach a larger number of people, that would make sense that you might consider distributing your ultra-cold at that place," she says. The Moderna vaccine volition work better, she says, "in areas where it might be more difficult to use upwardly such a large club or they may not have the [cold] storage."

The Centers for Disease Command and Prevention, the federal agency in accuse of vaccine distribution and decisions near which groups receive the first shots, has tried to discourage wellness departments and hospitals from going out and buying expensive freezers to accommodate the Pfizer vaccine. But according to a contempo report in Stat, wealthier hospitals are buying upward specialized freezers, raising concerns that hospitals with fewer resources or in rural areas will be left behind.

Moderna's announcement may atmosphere those fears, although since Pfizer's vaccine doses will exist urgently needed as well, it doesn't hateful that ultra-cold storage is no longer an outcome.

"I call back the best news is that there may be two vaccines that are effective because that means we can accomplish more people," says Finley. "We nonetheless need to bear witness that they're safe and they're effective and nosotros demand to build trust with the public — so at that place'southward still a ways to go, but this is adept news."

Despite the excitement and hopes riding on Pfizer and Moderna potentially having the get-go authorized COVID-19 vaccines, "this really isn't a race," says Liu. "Just by sheer numbers, we probably need multiple, multiple vaccines."

And in the end, she says, "it may be that the second one or the 50th one is actually a better vaccine."

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Source: https://www.npr.org/sections/health-shots/2020/11/17/935563377/why-does-pfizers-covid-19-vaccine-need-to-be-kept-colder-than-antarctica#:~:text=Neal%2FGetty%20Images-,The%20Pfizer%20COVID%2D19%20vaccine%20needs%20to%20be%20stored%20at,stints%20or%20in%20specialized%20freezers.

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