https://www.npr.org/sections/health-shots/2020/11/17/9355633...
In order to justify your stability, you need data to submit to the FDA (they don't take your word for it). When doing your initial stability studies, you try and collect data for the most ideal conditions - no refrigeration needed, stable for X years from room temperature to 30C (to account for conditions during shipment).
No doubt Pfizer lined up a number of early stability studies testing -80C, -50C, -20C, 0C, etc. They recognize that needing a -70C cold chain is a logistics hurdle. If they could avoid it at all, they would have pushed for it and had data to back it up.
How do you get this data for a large value of X without having to wait X years?
Though in practice it’s more complicated. Basically, make predictions based on accelerated testing and then validate them in real time tests. So, if things hold up at 3 and 6 months real time you can probably trust them over longer timeframes.
Let's keep things in perspective, please. This EUA is for Moderna's first product with any approval whatsover from the FDA. The lipid coating is a way for encasing the mrna vaccine in a kind of plastic for entering the cell.
