The Food and Drug Administration (FDA) said Thursday it is allowing more flexible shipping and storage temperatures for the Pfizer-BioNTech coronavirus vaccine. The change permits transportation and two-week storage at -25 degrees Celsius to -15 degrees Celsius, which is often found in pharmaceutical freezers and refrigerators. 

Pfizer previously said the vaccine has demonstrated stability when stored at these temperatures and the approval would allow greater flexibility for shipping, distribution and pharmacies' and vaccination centers' management of the shot.

The vaccine was first authorized to be stored in an ultra-cold freezer at temperatures between -80 degrees Celsius and -60 degrees Celsius, and can remain stored at these temperatures for up to 6 months. They are shipped in specially-designed thermal containers that can be used as temporary storage for a total of up to 30 days by refilling with dry ice every five days. 

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The ultra cold chain requirement for Pfizer’s vaccine has been a significant logistical snag in the country’s vaccination campaign. Thawed vials cannot be refrozen, and reports have documented wasted vials as they spoiled, amid a backdrop of limited supply issues nationwide. In some cases, providers scrambled to administer doses before the jabs spoiled, also true for Moderna, sometimes resulting in vaccinations among lower-priority individuals.

"Pfizer submitted data to the FDA to support this alternative temperature for transportation and storage," Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said in a release posted Thursday. "This alternative temperature for transportation and storage of the undiluted vials is significant and allows the vials to be transported and stored under more flexible conditions. The alternative temperature for transportation and storage will help ease the burden of procuring ultra-low cold storage equipment for vaccination sites and should help to get vaccine to more sites."

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The change does not apply to thawed vials, which can last in the refrigerator for five days before dilution, and six hours after dilution.

"We have been continuously performing stability studies to support the production of the vaccine at commercial scale, with the goal of making the vaccine as accessible as possible for healthcare providers and people across the U.S. and around the world," Albert Bourla, Pfizer's chairman and chief executive officer, said in a previous news release. "We appreciate our ongoing collaboration with the FDA and CDC as we work to ensure our vaccine can be shipped and stored under increasingly flexible conditions. If approved, this new storage option would offer pharmacies and vaccination centers greater flexibility in how they manage their supply." 

Fox News' Alexandria Hein contributed to this report.