I'm liking these new mRNA vaccines
Starting to read up on this new breed of vaccine--eg, from Pfizer and Moderna--and am liking what I'm reading.
(Caveat: I'm no expert in this field; merely trying to explain my lay-person-level understanding of the technology.)
Unlike vaccines currently and previously in use, these use mRNA (messenger RNA) which encodes the *instructions* for a cell to produce a certain protein which then serves as the "antigen" that will stimulate an immune response.
In contrast, prior vaccines often introduced the antigen itself.
The difference is significant: in one case, you are introducing the antigen--protein, or peptide, that is composed of amino acids, plus any other add-ons (sugars, carriers, etc). In the other, you are giving the cells of the body the *instructions* for how to build that antigen itself. (The term "antigen" is used to describe the entity that will cause the body to mount an immune response, which is the goal of all vaccines.)
mRNA is small. And *relatively* easy to make (uncomplicated).
Proteins can be very cumbersome to make, involving use of a "3rd party" such as bioengineered bacteria or yeast, as in large industrial bioreactor vats. Then they must be harvested and purified. In other words, labor- and time-intensive.
What mRNA vaccines do, is cut out a *lot* of the middlemen, by (like viruses themselves do) recruiting the cell's own machinery to do the work.
(Some vaccines even try to emulate the virus strategy, by using bioengineered/altered viruses--it's always a winning strategy to copy what nature, via natural selection, has already figured out--but here, again, the lab must manufacture the modified virus, using middlemen, a cumbersome process.)
Bravo! So, why wasn't this done before?
Well, this straegy has been in development for some time; it didn't magically appear when Trump instructed, "Warp Speed, Now!!" (That Trump *did* speed up the process by providing federal funds, is the LEAST *anyone* in that position would do, so no kudos to him from me, sorry.)
RNA molecules are notoriously delicate; just looking at them can practically destroy them. The world is a very dangerous place for RNA.
So, protective measures must be taken. One of those is the ultra-low storage temp that we hear so much about.
Moderna has taken another step, though, which is to encapsulate the mRNA with protective substances, which help ensure delivery of intact mRNA (think of it like how our phones deliver accurate text messages to us) to the cells, which then read and translate the messages into the appropriate protein.
Those proteins then get exposed to various elements of the immune system, which then orchestrates the body's immune response, and thus, defense.
Oh, and for those wondering what protein the mRNA codes for: it's a slightly modified version of the spike ("S" ) protein of the Covid19 virus, the main element involved in how the virus attaches to and then enters our cells.
There's much to learn and discuss, but just wanted to post a little intro for those who may have been curious. Who knows, if we're lucky, deployment of this tool may mark the beginning of our return to a "normal"--or at least pre-Covid--society.
Three cheers for Science and Scientists!
= new reply since forum marked as read
I have been wondering, too! 
Very interesting. Looking forward to hearing more about this as trials roll out. 
