Saints318
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Fascinating.Why Does Pfizer's COVID-19 Vaccine Need To Be Kept Colder Than Antarctica?
One of the two leading vaccine candidates requires deep, deep freezing. Here's how communities are working to solve for this and how the new Moderna vaccine could help.www.npr.org
Vaccines made from mRNA can be made much faster than older vaccines could, explains Margaret Liu, a vaccine researcher who chairs the board of the International Society for Vaccines and specializes in genetic vaccines. The problem, says Liu, is that mRNA is "really easily destroyed, and that's because there are many, many enzymes that will just break it apart."
Here's an analogy: Think of the vaccine as a chocolate bar that melts easily. Just as there are ways to keep the chocolate from melting into goo, there are things the drugmakers did to protect their COVID-19 vaccines.
The first step, Liu says, was to modify the mRNA nucleosides — the "building blocks" of the RNA vaccine. "They've used modified versions because those are more stable," she says. This would be like changing the chocolate recipe so it's not quite so melty.
The next step was to use lipid nanoparticles, which, Liu explains, "is kind of like putting your chocolate inside a candy coating — you have an M&M, so the chocolate doesn't melt."
But even with the stabilized building blocks and lipid coating, the mRNA could still fall apart easily, which is why the vaccine is frozen.
"Everything happens more slowly as you lower the temperature," Liu says. "So your chemical reactions — the enzymes that break down RNA — are going to happen more slowly." It's the same idea as freezing food to keep it from spoiling.
So what temperature is it at the time of injection? How do they raise the temperature to that point?