How the COVID-19 vaccines were created so quickly - Kaitlyn Sadtler and Elizabeth Wayne
In the 20th century, most vaccines took
well over a decade
to research, test, and produce.
But the vaccines for COVID-19 cleared
the threshold for emergency use
in less than 11 months.
The secret behind this speed
is a medical technology
that’s been developing for decades:
the mRNA vaccine.
This new treatment uses our body’s
existing cellular machinery
to trigger an immune response,
protecting us from viruses without
ever experiencing an infection.
And in the future, this approach might
be able to treat new diseases
almost as quickly as they emerge.
So how do these
revolutionary vaccines work?
The key ingredient is in the name.
mRNA, or messenger ribonucleic acid,
is a naturally occurring molecule
that encodes the instructions
for producing proteins.
When our cells process mRNA,
a part of the cell called the ribosome
translates and follows these instructions
to build the encoded protein.
The mRNA in these vaccines works
in exactly the same way,
but scientists use the molecule to safely
introduce our body to a virus.
First, researchers encode trillions
of mRNA molecules with the instructions
for a specific viral protein.
This part of the virus is
harmless by itself,
but helpful for training
our body’s immune response.
Then, they inject those molecules
into a nanoparticle
roughly 1,000 times smaller
than the average cell.
This nanoparticle is made of lipids,
the same type of fatty material that forms
the membrane around our cells.
But these lipids have been
specially engineered
to protect the mRNA on its journey
through the body
and assist its entry into the cell.
Lastly, the final ingredients are added:
sugars and salt
to help keep the nanoparticles intact
until they reach their destination.
Before use, the vaccine is kept at a
temperature of -20 to -80 degrees Celsius
to ensure none of the components
break down.
Once injected, the nanoparticles
disperse and encounter cells.
The lipid coating on each nanoparticle
fuses with the lipid membrane of a cell
and releases the mRNA to do its work.
At this point, we should note
that while the vaccine is delivering
viral genetic material into our cells,
it’s impossible for this material
to alter our DNA.
mRNA is a short-lived molecule
that would need additional enzymes and
chemical signals to even access our DNA,
let alone change it.
And none of these DNA altering components
are present in mRNA vaccines.
Once inside the cell, the ribosome
translates the mRNA’s instructions
and begins assembling the viral protein.
In COVID-19 vaccines, that protein
is one of the spikes typically found
on the virus’s surface.
Without the rest of the virus
this lone spike is not infectious,
but it does trigger our immune response.
Activating the immune system
can be taxing on the body,
resulting in brief fatigue, fever,
and muscle soreness in some people.
But this doesn’t mean
the recipient is sick—
it means the vaccine is working.
The body is producing antibodies to fight
that viral protein,
that will then stick around to defend
against future COVID-19 infections.
And since this particular protein is
likely to be found in most COVID variants,
these antibodies should reduce
the threat of catching new strains.
This approach offers significant
advantages over previous vaccines.
Traditional vaccines contain
weakened versions of live viruses
or amputated sections of a virus,
both of which required time intensive
research to prepare
and unique chemical treatments
to safely inject.
But mRNA vaccines don’t actually
contain any viral particles,
so they don’t have to be built
from scratch to safely adjust each virus.
In fact, every mRNA vaccine could have
roughly the same list of ingredients.
Imagine a reliable, robustly tested
vaccine that can treat any disease
by swapping out a single component.
To treat a new illness, researchers would
identify the right viral protein,
encode it into mRNA,
and then swap that mRNA
into the existing vaccine platform.
This could make it possible to develop
new vaccines in weeks,
giving humanity a flexible new tool
in the never-ending fight against disease.
