Remember back in December, when Covid vaccine distribution was first getting underway? Competing carriers joined together, like a truck-bound Santa Clause to deliver doses of the new drug to people who needed it desperately. Images of politicians getting inoculated flooded our newsfeeds. It provided a much-needed glimmer of hope at the end of a truly awful year.

Since then, excitement over vaccine delivery has ebbed. The news cycle marches on, and most of the public has long since stopped caring how items make it to their store shelves, front doors, or doctors' offices. It’s not that anyone has stopped relying on the vaccine to fix the bizarre situation we find ourselves in. It’s just that complex and sensitive freight services aren’t at the forefront of most people’s minds. Dry ice can only hold the world’s attention for so long. Vaccine distribution might be out of the spotlight (for now), but there’s an important new development in the works. Until now, one of the biggest obstacles has had to do with temperatures. Freezing temperatures, that is.

As of February, vaccines from Pfizer and Moderna have been approved by the CDC to inoculate against Covid-19. While Moderna’s jab can be stored at -20 degrees Celsius, the Pfizer inoculation originally had to be kept at -70 degrees Celsius. (That’s less than the lowest temperature on record at the Klinck research station in Greenland, for anyone keeping track at home.) Now, Pfizer has submitted new data to the FDA showing that its vaccine can be stored between -25 and -15 degrees Celsius. If approved, the ramifications could be huge.

Storing a shot at -70 degrees Celcius requires either a specialized freezer (one that is so cold that most hospitals don’t have it on hand) or careful packaging in dry ice. In August, a Pfizer scientist told the CDC that freezers containing Covid vaccines should not be opened more than twice per day, and should not stay open for more than a minute at a time. Relaxing these requirements would not only reduce costs but make the vaccine much more easily available in parts of the world that might not otherwise have access.

But why must the vaccines be kept in this frigid state to begin with, you ask? The reason has to do with their ingredients. The primary one is ‘nucleoside modified messenger RNA’ or mRNA. mRNA works by teaching our immune systems to fight off Covid-19 from the inside out. Once injected, it induces human cells to create a coronavirus protein. That protein then triggers an immune response, which we use to make antibodies. The antibodies are what staves off the virus, should we become infected down the road. This is great news, but there’s a catch. In addition to being medically useful, mRNA is also really delicate. Unless it is kept at temperatures that rival an Arctic winter, it will break down before ever reaching a patient’s arm.

This creates some particularly urgent challenges relative to most vaccines. While most pharmaceuticals require chilled freight services, not all need to be kept at a temperature this cold. Regular flu vaccines, for example, can be stored at around 2-8 degrees Celsius and can live in a refrigerator for months at a time. Now, if Covid vaccines can be stored in a more forgiving setting, it could save countless costs, man-hours, and lives around the globe. Amesh Adalja, at the Johns Hopkins Center for Health Security, says it best, telling Reuters that the higher temperatures would ‘greatly expand the ability to use this vaccine in many parts of the world (or even the U.S.) that do not have the capacity for deep freeze storage’.

In the meantime, cold chain logistics continues to save countless lives….