Pfizer reduces ultra-cold requirements for its COVID-19 vaccine
New data submitted to the U.S. Food and Drug Administration from Pfizer claims its mRNA COVID-19 vaccine is stable for longer periods at warmer temperatures than previously thought. 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.
“Our top priority was to quickly develop a safe and effective vaccine and make it available to the most vulnerable people in the world in order to save lives,” says Sahin. “At the same time, we have continuously collected data that could enable storage at around -20 °C (-4 °F). The data submitted may facilitate the handling of our vaccine in pharmacies and provide vaccination centers an even greater flexibility.”
Pfizer’s candidate is not the only mRNA COVID-19 vaccine to reach the market. Closely following Pfizer’s emergency FDA approval last year was another mRNA vaccine from Moderna, which did not require the same degree of ultra-cold storage.
Moderna’s mRNA vaccine is claimed to be stable for up to six months at normal freezer temperatures between -25 °C to -15 °C (-13 °F to 5 °F). Explaining the discordancy in storage conditions between the two similar mRNA vaccines, Moderna claims its unique lipid nanoparticle formulation allows for greater stability at higher temperatures compared to Pfizer’s candidate.
Speaking to NPR last November, a Moderna spokesperson also explained the company has garnered significant experience over several years developing a number of other mRNA vaccines. This perhaps gives it greater insight into how stable its mRNA vaccines can be in various temperature conditions.
"Now we don't need [ultra-cold conditions] as the quality of product has improved and [it] doesn't need to be highly frozen to avoid mRNA degradation," says Moderna spokesperson Colleen Hussey.
Peter English, former chair of the British Medical Association’s Public Health Medicine Committee, says it is possible Pfizer will broaden storage temperature requirements for its COVID-19 vaccine even further as it learns more over time.
“I would not be surprised if, as time goes by and the period of storage prior to testing increases, they will be able to increase this period,” says English. “This is likely to make the infrastructure requirements considerably easier.”