The new recommendations suggest the vaccine is stable for two weeks in freezers around -15 °C (5 °F), allowing for significantly more flexibility in shipping and storage methods.

The first COVID-19 vaccine to be approved last year for emergency use in the United States was based on cutting-edge mRNA technology. Developed by German company BioNTech, with assistance from pharma giant Pfizer, the vaccine demonstrated incredible efficacy but it came with a caveat. The vaccine needed to be kept at ultra-cold temperatures to prevent degradation.

Standard pharmaceutical freezers deliver temperatures between -25 °C to -15 °C (-13 °F to 5 °F). Ultra-cold freezers, on the other hand, can keep items at temperatures between -80 ºC and -60 ºC (-112 ºF to ?76 ºF).

A major challenge in effectively distributing Pfizer's COVID-19 vaccine is that many parts of the world do not have the ultra-cold chain delivery infrastructure to keep the vaccine at the temperatures required. Pfizer has developed novel dry ice packaging to help broadly distribute its vaccine but the ultra-cold storage requirement has inevitably been a difficult and expensive problem to overcome.

Now, the company claims new data suggests its vaccine is stable for at least two weeks in more normal freezer temperatures of between -25 °C to -15 °C (-13 °F to 5 °F). This new data has been supplied to the FDA in the hopes of updating the details of its emergency use authorization.

CEO of BioNTech, Ugur Sahin, suggests this new recommendation has arisen out of continual stability studies that have been ongoing since mass production of the vaccine commenced late last year. Because the mRNA technology behind this vaccine was so new the company has been conservative with its storage recommendations until further data could be collected.