Via press release from the FDA:
Today, the U.S. Food and Drug Administration announced that it is allowing undiluted frozen vials of the Pfizer-BioNTech COVID-19 Vaccine to be transported and stored at conventional temperatures commonly found in pharmaceutical freezers for a period of up to two weeks. This reflects an alternative to the preferred storage of the undiluted vials in an ultra-low temperature freezer between -80ºC to -60ºC (-112ºF to -76ºF). The change is being reflected in updates to the Fact Sheet for Healthcare Providers Administering Vaccine (Vaccination Providers).
“Pfizer submitted data to the FDA to support this alternative temperature for transportation and storage. 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,” said Peter Marks, M.D., Ph.D., director of the FDA’s Center for Biologics Evaluation and Research.