PORTLAND, Ore. — The Pfizer and Moderna coronavirus vaccines have a lot in common. Both vaccines require two doses, both were made using mRNA technology and each of them is about 95 percent effective.
But they are different in one key area — storage temperature. And that difference will impact who gets which vaccine.
Moderna says their vaccine must be kept at -4 degrees Fahrenheit. That's about as cold your typical freezer where you keep a frozen pizza or those peas you'll never eat.
But the Pfizer vaccine requires extremely cold temperatures, more like -94 degrees Fahrenheit. That means the storage temperature is colder than winter in Antarctica and much too cold for your typical freezer.
In fact, the Pfizer vaccine requires 'ultra-cold storage.' And as you can imagine, there aren't that many ultra cold freezers around. You can't just drive down to the local appliance store to get one.
That's why you've probably heard talk about the "ultra-cold chain." That refers to the logistical network health officials are trying to put together — keeping that Pfizer vaccine at -94 degrees every step of the way.
The cold storage chain is also one of the reasons why urban areas, with larger hospitals and more ultra cold storage, are expected to receive more of the Pfizer vaccine. Whereas, rural areas will receive more of the Moderna vaccine.