- [Reporter] This is a spike protein.
It's what gives the coronavirus its unmistakable look
and scientists think it may be the key to why new variants
of the virus are becoming more transmissible.
- A new study by the CDC is raising the alarm
on the coronavirus variant spreading across the country.
- The fast-spreading COVID-19 variant
first found in the UK is now evolving in a way
that could make existing vaccines less effective.
- [Reporter] New research shows
that the more transmissible variant from the UK,
called B117, will likely become the most common version
of the virus in the US.
- The big concern is that, with more transmissible variant,
you have more cases and you have more chance
for superspreading events and epidemic surges
which overwhelm our healthcare systems.
- [Reporter] Here's the science
behind why these new variants are spreading faster
and what this could mean for vaccines.
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Like other viruses, when the coronavirus replicates,
small genetic mistakes, or mutations, can occur.
- You can be almost certain
that as long as there's a lot of virus
circulating in the community, there will be the evolution
of mutants because that's what viruses do.
- Many of those do nothing.
Some of those actually confer a survival benefit
for the virus to transmit more effectively, for instance.
- [Reporter] Abraar Karan is a global health physician
who has been studying the coronavirus pandemic.
- And so, as it does that,
it has a better chance of spreading to new hosts
and continuing to replicate in those hosts.
- [Reporter] Karan says this is likely what is happening
with the new, more transmissible variants
appearing around the world.
Recent research has shown that a number
of these new versions of the virus have mutations
that affect the spike protein.
Take a look at this model of the coronavirus.
You can see each spike protein
is made up of three identical parts known as protomers.
These protomers have the ability to change their position
from closed to open, affecting how easily
they can bind to and infect human cells.
- You can visualize it like a flower.
So you've got petals on the outside,
the really obvious thing that you see.
There are three of them.
The three of them have to bind to the receptors.
- [Reporter] Jeremy Luban is a virologist
who studies the coronavirus.
He explains that when the protomers are down,
infection is more difficult.
But when these parts are up and open, it's much easier.
In the first version of the coronavirus
that originated in China in 2019,
these protomers usually had a closed shape,
which may have made it less transmissible
than some more recent versions of the virus.
This is another view of a spike protein
that helps to show where these mutations occur.
In the winter of 2020,
one mutation, known as D614G, emerged.
It appears in this region of the spike protein.
This mutation made it more likely for the spike
to have an open shape, increasing the virus' ability
to infect human cells.
Soon after the mutation emerged,
variants that had it took over.
- So by June, pretty much all the viruses around the planet
had this change, this mutation.
Our belief is that it supplanted the original virus
because it was more transmissible.
- [Reporter] Luban thinks this is what is happening
with some of the new variants
that are emerging around the world as well.
- In the United Kingdom,
that variant really expanded very rapidly.
It was first seen in September
and now it's the dominant version of the virus
circulating in the United Kingdom.
Does indeed appear as if the same thing happened
in South Africa.
- [Reporter] Another element
that affects the spike protein is antibodies.
These are proteins that defend the body
against the coronavirus by blocking the ability
of the spike protein to attach to cells,
which prevents the virus from infecting.
Antibodies are produced by the immune system
in response to infection or vaccines,
and so far, the new coronavirus variants
scientists are worried about all have mutations
that affect the spike protein.
Here are some that scientists are focusing on.
The first is called N501Y, which was first detected
in the variants from the UK and South Africa
in the second half of 2020.
This mutation is located in a region of the spike protein
known as the receptor binding domain, or the RBD.
This is the main location
where the virus attaches to human cells and infects them.
The N501Y mutation seems to be helping the virus bind,
which could help explain the higher transmissibility.
The second mutation
that scientists are focusing on is called E484K.
It's found in variants
from South Africa and Brazil and reduces the ability
of certain antibodies to bind to the RBD,
which helps the virus' chances of infecting cells.
- What the antibody recognizes is the shape.
If you're playing with blocks and you have triangles
and circles and you have to fit them
into the appropriate holes,
you can't fit a circle into a triangular hole.
It's analogous to that.
If the virus then changes
so that it's no longer a triangular hole
but it's a circular hole,
then the antibody will no longer fit.
- [Reporter] Scientists have also found
that some of the new coronavirus variants have parts missing
in a region that comes off the side of the spike protein.
This is known as the N-terminal domain.
- Some of those mutations
are removing surfaces of the protein
that other antibodies bind to.
If the virus mutates that surface or deletes it,
those antibodies are no longer going to work
to block the virus.
- [Reporter] Scientists say this may help explain
why current vaccines may be becoming less effective
against some new variants.
This is why experts are urging caution.
- Variants are gonna continue emerging
and we need a public health strategy that addresses it.
We have to focus on getting better ventilation.
We have to get people better personal protection;
better, higher-grade masks that can filter better;
we have to test; we have to trace;
we have to isolate the fundamentals of epidemic control.
- [Reporter] And Karan says that while vaccines
should still be effective in preventing severe illness,
a booster variant shot may be needed later in the year.
- They work extremely well right now,
right, With Moderna and Pfizer 95% vaccine efficacy.
They will start to work less well
against some variants into the future,
but that is to be expected
and that is why vaccines will be a major part
of COVID control for the foreseeable future.
- [Reporter] Experts continue to emphasize
the importance of getting vaccinated
along with other strategies to keep transmission low
and stop the spread.
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