- [Narrator] New coronavirus variants
are making COVID-19 more transmissible.
Why?
Basically, inside the bodies of people who are infected,
the coronavirus is mutating and evolving.
- Viruses, you're making billions upon billions
of new copies
and you're getting so many generations of the virus
that it's much easier for viruses to evolve
and adapt over time.
- [Narrator] Now, this coronavirus mutates slowly
compared to other kinds of viruses, like the flu or HIV.
On average, only two new mutations a month worldwide.
- The virus basically jumps
from one person to the other without changing
because it's so quick.
It infects cells very quickly.
It makes copies very quickly.
Even before the immune system
has had a chance to put any pressure on the virus,
it's already gone and infected somebody else.
- This virus fortunately has a proofreading mechanism.
However, it does accumulate mutation over time.
- [Narrator] And in certain people
who harbor the virus for long periods of time,
weeks or months,
you get more of these mutations stacking up.
- Many of those individuals have immune deficiency problems.
Their immune system doesn't work very well
and so they can't clear the virus,
generating more and more mutations.
- [Narrator] And though some of these people
don't display symptoms, they shed lots of virus
over the course of their lengthy infections.
- Those isolated events are spilling out into the community
and now leading to large numbers of new infections.
- [Narrator] Take variant B.1.1.7,
first documented in the UK.
- We were one of the groups that discovered it.
There were eight spike mutations.
- [Narrator] Meaning mutations in the genes
that make the protein
that forms the coronavirus' distinctive spikes,
which cover its outer surface
and dock to the cells in our body.
- These mutations allow it to bind more tightly
to the ACE-2 receptor that's on the human cell,
which appears to allow it
to replicate more efficiently as well.
- [Narrator] All proteins, including the spike protein,
are built from subunits called amino acids.
Of the eight changes
in each piece of this variant's spike protein,
two are deletions of a single amino acid
and six are amino acid substitutions.
These different components
change the shape of the spike protein slightly,
which appear to make it easier for the coronavirus
to invade a human cell.
As a result, the UK variant is about 50% more transmissible
than the original version due, it seems,
in large part to one of these substitutions.
- In just a span of a few weeks,
it's overtaken all of the other circulating strains
in the UK.
It's a competition between the new variant
and the variant that's already present in the community.
- The amount of virus in the nose
appears to be higher in people with the new variant
as compared to other strains.
And that explains potentially
why we are seeing higher transmission rates.
- [Narrator] In other words,
a person infected with this variant
might be exhaling or expelling more virus,
meaning anyone breathing the same air
would be more likely to get infected.
- That is a major concern
because that means the virus can spread more quickly
amongst the population.
- [Narrator] Experts are concerned that the UK variant
may spread quickly outside the UK, including in the US.
There are other variants that have emerged as well.
One in Brazil.
Another in South Africa.
Both share one of the UK variant's spike mutations
and both appear more transmissible
than the original version.
Across these variants,
additional mutations may help the coronavirus
evade the antibodies developed by our immune systems
in response to older versions of the virus,
while other mutations might make the new strains
even more infectious.
- The fact that these strains are more transmissible
also means that we need to do an even better job
of adhering to all of the public health interventions.
- [Narrator] A new variant has also emerged in California.
These aren't the first examples of a COVID-19 variant
replacing an earlier version of the virus.
Last spring, the D614G variant emerged
and replicated more efficiently
than the original Wuhan version.
- This variant quickly spread worldwide
and became the dominant strain.
- So we've already seen it happen once with this virus.
- [Narrator] But this time, we've got vaccines.
- [Jonathan] A SARS-CoV-2 strain
that can escape from a vaccine would be a disaster.
- [Narrator] The vaccines still appear to work
against the UK variant.
But the variants from South Africa and Brazil
are more concerning.
The vaccines may be less effective against them
since the vaccines trigger the production of antibodies
custom-made to fight an earlier version of the virus.
- If the vaccine doesn't elicit enough of an immune response
that those variants may not be as well covered
by the vaccine.
- The variants are probably going to lead to small increases
in the number of vaccine failures.
But the question is, how big is that jump?
And I think that's the thing we don't know yet.
- [Narrator] The variants make the need
for widespread vaccination even more urgent.
Experts want fewer opportunities
for these variants to find their way back
to people with compromised immune systems
where they could mutate further, becoming super-variants.
The Pfizer/BioNTech and Moderna vaccines
both rely on messenger RNA,
a bit of genetic material
that codes for the coronavirus spike protein.
When it's injected into our bodies,
our immune system learns to recognize a piece of the virus
so that if the real thing ever infects us,
we've already got the weaponry to fight it off.
The current vaccines contain the RNA sequence
of the original coronavirus spike protein.
But one advantage of using RNA
is you can just update the vaccine
with the sequence of the new, mutated spike protein.
Both vaccine makers are working to do just this
by developing an additional booster shot.
- I do worry about having to do catch up with the vaccine.
- [Narrator] One way to keep up with COVID and fight it off
is to ramp up our surveillance by sequencing the virus.
That is, reading out its genetic signature
to identify mutations and new variants as they emerge.
- Yes, if we do it right, we'll stay ahead of the virus.
So we'll see these things popping up.
- Right now, I would say that we're largely blind
in this country.
We're not doing a sufficient job
of monitoring all of the viral variants
and figuring out why the outbreak is so out of control
in certain regions of the country.
- [Narrator] Tracking these variants more closely
will also help keep our testing up to date
so we can actively detect
the coronavirus strains in circulation.
As more and more people are vaccinated,
infections are expected to drop gradually.
But we're racing against a fleet
of increasingly transmissible coronavirus variants.
- So we need to get a move on.
- If we can get people vaccinated,
I think that's the fastest way out of this nightmare.
(dramatic instrumental music)