Why so many Covid-19 variants are showing up now

On November 5th, 2020,

the United Kingdom
went into lockdown.

They were trying to control
a spike in Covid-19 cases.

And, if you look at
the chart of cases,

it seemed to work.

But, despite having the same
lockdown measures,

infections in Kent, an area
outside of London, were still rising.

In early December, the overall drop in cases
led the country to relax restrictions anyway.

And then this happened.

It wasn’t until around this time
that researchers realized

that somewhere in Kent,
the virus itself had changed.

It was a new variant.

It was more contagious.

And it was spreading.

By the time scientists gave it a name,
it had spread to most of southeast England.

Two months later,
it was in 30 other countries.

Five months later, it was the most common
form of the virus found in the United States.

Lately, more and more variants are emerging
in various places around the world.

So why are they showing up now?

And what does this mean for the pandemic?

Viruses are very simple.

They’re basically just a shell of protein
surrounding some genetic material:

either DNA or RNA.

That genetic material
is made up of molecules

that can be represented as
a series of letters, like this.

Each part of this code contains instructions

for how to make one specific protein
that allows the virus to function.

A virus has one goal:
to make more of itself.

But because it’s so simple,
it can’t do that on its own.

So it uses you.

Every time a virus infects a person,
it uses their cells to make copies of itself--

replicating this complex code
again, and again, and again.

But eventually,
it makes a mistake.

Sometimes it deletes
or adds a letter.

Sometimes it flips them around.

That mistake is called a mutation,

and it slightly changes the instructions
for making the virus.

That slightly altered virus
is a variant.

Since viruses are constantly going
through this copying process,

it’s normal for them
to change over time.

For example, this chart shows
some of the mutations

the SARS_CoV2 virus has made
since December of 2019.

Most of the time, these mutations are harmless,
or even make the virus weaker,

and they quietly disappear without
making any notable difference.

But other times, a series of mutations occur
that give the virus a slight edge over us.

Which is what scientists started to notice
with SARS_CoV2, back in September of 2020.

“You're seeing specific mutations
that do allow the virus

to bind human receptors better,
and enter cells better.”

Coronaviruses are covered
in spike proteins,

that they use to bind with
and infect human cells.

The thing is, that binding
isn’t a perfect fit.

So it doesn’t always get
past the cell’s defenses.

But the B.1.1.7 variant, which scientists
later renamed the “Alpha” variant,

has multiple mutations
on the spike protein:

Mutations that make it easier
for the virus to bind with cells.

Which can help make
the virus more transmissible.

Which led it to become a dominant strain
in many places around the world.

But if SARS_CoV2 has
been mutating all along,

why do the variants today,
like this Alpha variant,

suddenly seem
so much worse?

It’s important to remember that a virus
doesn’t make active decisions.

It’s not as if it creates a
strategy within your cells.

Mutations are random errors.

But the longer a virus is around,
and the more people it infects,

the more it will change.

And the more those
changes accumulate,

the more chances the virus has to evolve
into something more dangerous.

These four variants, considered “variants of
concern” by the World Health Organization,

all have mutations
on the spike protein.

Delta, the most recent addition to this list,
has been referred to as a “double mutant,”

because, while it has many different mutations,
it has two significant ones we’ve seen before:

This mutation seems to make
the virus more transmissible.

And a version of this one,
found in two other variants,

makes it easier for the virus to reinfect
people who have already had Covid-19--

meaning, these two mutations may have
evolved to dodge our natural immune response.

Fortunately, the immune response
we get from the vaccines

is much stronger than our body’s
natural immune response.

So, while we may see variants that make
our vaccines somewhat less effective,

most experts think it’s unlikely one will emerge
that completely evades our vaccines.

But that doesn’t mean it can’t happen.

“If you give the virus enough
time and replicative cycles,

it will sample a very large
evolutionary space,

and find a solution to the
problem we've presented it--

which is vaccination
and widespread immunity.”

But even if SARS_CoV2
doesn’t get to that point,

as long as the pandemic continues,
and as long as the virus continues to spread,

it will continue to make copies of itself.

So if we want to stop the variants,

we need to stop the virus.

The virus has evolved. But it hasn’t
morphed into something unrecognizable.

The vaccines we have still
protect against all the variants.

The trouble is, we aren’t getting those
vaccines around the world fast enough.

Which is only giving the virus
more time to change,

and ravage areas of the world
that are still waiting.

The rise of variants is a reminder
that the pandemic isn’t over.

Even if it feels like
it is to some of us.

“We need to stop this, because we
don’t want a variant that affects immunity.

And so that involves stopping
replication everywhere.”