The need for ultra-low-temperature freezers to store coronavirus vaccines might not present as much of a hurdle as some fear — for now. The second approved vaccine, by Moderna, can be stored at around -4 degrees Fahrenheit, compared to Pfizer's required -94 F. That allows a wider range of storage options. Should AstraZeneca's vaccine receive approval as well, those options could expand even further. It can remain stable at a comparatively balmy 40 F. But as associate professor Kristen Parrish of Arizona State University's School of Sustainable Engineering and the Built Environment explained, as long as the doses are in high demand, even their shipping containers provide enough temporary cold to keep them stable.