Colder than winter in Antarctica.

We’re talking -70 degrees C, the temperature necessary to store Pfizer’s COVID-19 vaccine as a means to slow the countless enzymatic reactions that destabilize mRNA. Compare this to Moderna’s vaccine that has proven stable at -20 degrees C (achievable by most standard freezers), which it attributes to unique lipid nanoparticle coating. As a less technical work-around, Pfizer is planning to distribute its vaccine in dry ice where it can safely stay for 15 days if dry ice is replaced every 5 days. Once thawed it can stay refrigerated for 5 days, but the dry ice packaging can be opened no more than twice daily for no more than 60 seconds at a time—does anyone else foresee user error entering the equation? Moderna’s, on the other hand, can be stored in a standard freezer for up to 6 months, in a refrigerator for 30 days, and room temperature for 12 hours. On a final positive note, these shelf lives may prove longer with longer evaluation time. TBL: Well-orchestrated vaccine administration logistics may allow you to cancel that Amazon order for an ultra-freezer. | Simmons-Duffin, NPR 2020